TWI605271B - Producing method for light diffusion film - Google Patents

Description

Method for manufacturing light diffusion film

The present invention relates to a method of producing a light diffusing film. In particular, the present invention can be easily obtained by using a linear light source by including a louver structure region for diffusing anisotropic light of incident light and a column structure region for diffusing incident light into isotropic light. A method of manufacturing a light-diffusing film having a good incident angle dependency and a wide light diffusion incident angle region in light transmission and diffusion.

Conventionally, in a liquid crystal display device, a predetermined image can be recognized by light emitted from a light source (internal light source) provided inside the device.

However, in recent years, there has been an increase in the chance of viewing a liquid crystal display screen outdoors due to the spread of mobile phones, televisions, and the like, and the problem that the light intensity from the internal light source is negative to external light and it is difficult to recognize a predetermined screen has arisen. .

Further, in mobile applications such as mobile phones, the power consumption of the internal light source of the liquid crystal display device accounts for a large proportion of the total power consumption. Therefore, when the internal light source is often used, the battery duration is shortened.

Therefore, in order to solve such problems, a reflective liquid crystal display device using external light as a part of a light source has been developed.

In the case of the above-described reflective liquid crystal display device, since external light is used as one of the light sources, the stronger the external light, the more vivid the image can be recognized, and the power consumption of the internal light source can be effectively suppressed.

Further, in such a reflection type liquid crystal display device, there has been proposed a method in which external light is efficiently transmitted and taken into the interior of the liquid crystal display device, and The external light is used as a part of the light source, and a light diffusion film for efficiently diffusing light is provided (for example, see Patent Document 1).

More specifically, Patent Document 1 discloses a liquid crystal device 1112, as shown in FIGS. 29a to 29b, which has a liquid crystal cell in which a liquid crystal layer 1105 is sandwiched between an upper substrate 1103 and a lower substrate, and is disposed under A light reflecting plate 1110 on the substrate 1107 side and a light control plate (light diffusing film) 1108 disposed between the liquid crystal layer 1105 and the light reflecting plate 1110.

Further, a light control plate 1108 for selectively scattering light incident at a predetermined angle and transmitting light incident at an angle other than a predetermined angle is provided, and the light control plate 1108 selectively enters light at a predetermined angle. The scattering axis 1121 in which the direction of scattering is projected onto the surface of the light control plate 1108 is in the direction of the substantially 6 o'clock direction inside the liquid crystal cell.

Here, as a light-diffusing film used in a reflective liquid crystal display device, it has been disclosed that a specific photo-curable composition is irradiated with an active energy ray by using a linear light source, thereby making a high refractive index in either direction along the film surface. A light-diffusing film in which a plate-like region and a plate-like region having a low refractive index are alternately arranged in parallel to form a louver structure region in the film (for example, Patent Documents 2 to 3).

In other words, Patent Document 2 discloses a light control film in which a light-control film (light-diffusion film) irradiates a film-like composition containing a plurality of compounds having a polymerizable carbon-carbon double bond with ultraviolet rays from a specific direction. The composition obtained by curing the composition selectively scatters incident light of a specific angular range, and at least one compound contained in the composition has a plurality of aromatic rings and one polymerizable carbon-carbon double bond in the molecule. Compound.

Further, Patent Document 3 discloses a photocurable composition and a light control film obtained by curing the photocurable composition, which comprises a carbon-carbon double bond having polymerizable properties in a molecule. A fluorene compound (A), a cationically polymerizable compound (B) having a different refractive index from the fluorene-based compound (A), and a photocationic polymerization initiator (C).

On the other hand, as another type of light diffusing film used in a reflective liquid crystal device, a light diffusing film has been disclosed which is formed by irradiating a specific photocurable composition as a living energy line as parallel light. Thereby forming along the film thickness direction of the film A column structure region in which a plurality of pillars having a high refractive index are arranged in a region having a low refractive index (for example, refer to Patent Documents 4 to 6).

That is, Patent Document 4 discloses a method for producing a diffusion medium grease, characterized in that a composition containing a photocurable compound is formed into a sheet shape, and the sheet is irradiated with parallel rays from a predetermined direction P to cure the composition. Further, a method of manufacturing a diffusion medium (light diffusion film) in which an aggregate of a plurality of rod-shaped solidified regions extending in parallel with the direction P is formed inside the sheet, wherein the linear light source and the sheet are sandwiched in parallel with the direction P A collection of configured cylinders and light illumination through the barrel.

In addition, in the manufacturing apparatus of the light control film, the manufacturing apparatus is configured to move the photocurable resin composition while arranging the linear light source so as to face the photocurable resin composition film. At least one of the film and the linear light source is formed by irradiating light from the linear light source to cure the photocurable resin composition film to form a light control film (light diffusion film), wherein the axial direction of the linear light source crosses the moving direction The plurality of thin plate-shaped light-shielding members that are opposed to each other are disposed in a manner that a predetermined interval is formed between the photocurable resin composition film and the linear light source in a direction substantially perpendicular to the moving direction, and is shielded from light. The side of the module facing the photocurable resin composition film is in the same direction as the moving direction.

Further, Patent Document 6 discloses a reflection type projection screen including a diffusion layer (diffusion film) having a top surface facing upward as a light absorption surface and an inclined surface facing downward as a reflection surface. The Fresnel surface of the linear Fresnel element is disposed to cover, and has a light diffusion characteristic that does not diffuse incident light larger than a predetermined angle, wherein the diffusion layer passes through the first light irradiation step and the second light irradiation step In the first light irradiation step, the photocurable resin composition is irradiated with parallel light from a predetermined direction by a photomask having a light passage region and a light non-passage region, and the irradiated portion is cured to be incomplete. In the second curing step, the photo-curable composition is further irradiated with parallel light having a substantially constant light intensity distribution, and the curing of the photocurable composition is completed, and the film is provided in the film. a separation structure having a photocurable composition in the film The base body to be formed and a plurality of columnar structures oriented in the matrix in such a manner as to extend in the direction in which the parallel light is irradiated and having a refractive index different from that of the substrate.

Patent Document 1: Japanese Patent No. 3480260 (Application Patent Range, Drawing, etc.)

Patent Document 2: Japanese Laid-Open Patent Publication No. 2006-350290 (Application Patent Range, Drawing, etc.)

Patent Document 3: Japanese Laid-Open Patent Publication No. 2008-239757 (Application No. Patent Specification, Drawing, etc.)

Patent Document 4: Japanese Patent No. 4,095,573 (Application Patent Range, Drawing, etc.)

Patent Document 5: Japanese Laid-Open Patent Publication No. 2009-173018 (Application Patent Range, Drawing, etc.)

Patent Document 6: Japanese Laid-Open Patent Publication No. 2008-256930 (Application Patent Range, Drawing, etc.)

However, in the light-diffusing film having the louver structure region disclosed in Patent Documents 1 to 3, it has been found that such an arrangement does not sufficiently enlarge the incident angle region of the incident light that can diffuse light (hereinafter, it is sometimes called The light is diffused into the incident angle region, and further, the opening angle of the diffused light may be narrow.

Further, in the light-diffusing film having the columnar structure region disclosed in Patent Documents 4 to 6, it has been found that the reflection of light in the film tends to be uneven as compared with the light-diffusing film having the louver structure region. Therefore, the fluctuation of the light diffusion characteristics based on the incident angle of the incident light is large, and it is difficult to exhibit a good incident angle dependency.

Further, in Patent Documents 1 to 6, only a light diffusion film having a louver structure region alone or a column structure region alone has been disclosed, and therefore, a method for manufacturing a light diffusion film having both of the structural regions in a single film is disclosed. Not stated, there is no record or revelation.

Therefore, the present inventors have made intensive efforts in view of the above circumstances, and as a result, It has been found that by providing a louver structure region for anisotropic light diffusion of incident light and a column structure region for isotropic light diffusion of incident light, it is possible to obtain light having good incident angle dependency and light. A light diffusing film having a wide diffusing incident angle region.

Further, the present inventors have found that the first active energy ray irradiation for forming the louver structure region and the second active energy ray irradiation by the irradiation light parallelization unit for forming the pillar structure region are sequentially performed, thereby The present invention can be completed by easily obtaining a light-diffusing film having the above characteristics by using a linear light source.

That is, an object of the present invention is to provide a light diffusion film which can easily obtain a favorable incident angle dependency in light transmission and diffusion by a linear light source and has a wide light diffusion incident angle region.

According to the present invention, it is possible to provide a method for producing a light-diffusing film which has a first structure region for causing incident light to diffuse anisotropic light, and a method for producing the light-diffusing film. The method for producing a light-diffusing film in a second structural region for isotropically diffusing incident light includes the following steps (a) to (d): (a) a step of preparing a composition for a light-diffusing film; (b) a step of applying a composition for a light diffusion film to a process sheet to form a coating layer; (c) irradiating the coating layer with a first active energy ray, and forming a first structural region under the coating layer a step of arranging a plurality of plate-like regions having different refractive indices in a louver structure region alternately arranged in any direction along the film surface, and leaving a region where the louver structure is not formed in a portion above the coating layer; Further, the coating layer is further irradiated with the second active energy ray, and a plurality of pillars having a relatively high refractive index as the second structural region are formed in a region where the louver structure is not formed, and are formed in a region having a relatively low refractive index. Column structure area The step of irradiating the coating layer with the irradiation light from the linear light source by the irradiation light parallelizing unit as the second active energy ray irradiation.

In other words, in the method for producing a light-diffusing film of the present invention, the first active energy ray irradiation for forming the louver structure region and the second irradiation illuminating unit for forming the pillar structure region are sequentially performed. The active energy ray is irradiated to produce a light diffusing film.

Therefore, even when a linear light source is used for both the first and second active energy ray irradiation, it is possible to efficiently form an anisotropic light for diffusing incident light in the film in a single film. A louver structure region of the structure region and a pillar structure region as a second structure region for diffusing the incident light into the film in the isotropic light.

As a result, by repeating the incident angle dependency of each structural region, it is possible to easily obtain a light diffusion film that suppresses fluctuation in light diffusion characteristics.

Further, by making the incident angle dependency of each structural region different, it is possible to easily obtain a light diffusion film that effectively enlarges the light diffusion incident angle region.

In the present invention, the "light-diffusing incident angle region" refers to an angular range of incident light corresponding to the emitted diffused light when the angle of incident light from the point light source is changed for the anisotropic light-diffusing film. . Details of the above-described light diffusion incident angle region will be described later.

In addition, "good incident angle dependency" means that the difference between the incident angle region (light diffusion incident angle region) of the film which generates the diffused light of the incident light and the other incident angle region where no light diffusion occurs is clearly controlled.

Further, "anisotropic" in the present invention means that the expanded shape of the diffused light has anisotropy, and "isotropic" means that the expanded shape of the diffused light has isotropy, but Said.

Further, in the method of producing the light-diffusing film of the present invention, it is preferable that the irradiation light parallelizing unit is composed of a plurality of plate-like members, and when viewed from above the film, the plurality of plate-like members are arranged in parallel.

By doing so, it is possible to easily change the irradiation light from the linear light source into parallel light having a predetermined parallelism in the second active energy ray irradiation.

Further, when the method for producing a light-diffusing film of the present invention is carried out, it is preferable to The adjacent plate-like members of the plate-like members are spaced apart from each other by a value in the range of 1 to 100 mm.

By doing so, it is possible to more efficiently change the irradiation light from the linear light source into parallel light having a predetermined parallelism in the second active energy ray irradiation.

Further, in carrying out the method for producing a light-diffusing film of the present invention, it is preferable to arrange the irradiation light parallelizing unit in a direction in which the plate-like member intersects the axial direction of the linear light source when viewed from above the film.

By doing so, it is possible to more efficiently change the irradiation light from the linear light source into parallel light having a predetermined parallelism in the second active energy ray irradiation.

Further, in carrying out the method for producing a light diffusing film of the present invention, it is preferred that the irradiated light parallelizing unit is an aggregate of a plurality of cylindrical members.

By doing so, it is possible to more easily change the irradiation light from the linear light source into parallel light having a predetermined parallelism in the second active energy ray irradiation.

Further, in carrying out the method for producing a light-diffusing film of the present invention, it is preferable that the maximum diameter of the cylindrical member is in the range of 1 to 100 mm.

By doing so, it is possible to more efficiently change the irradiation light from the linear light source into parallel light having a predetermined parallelism in the second active energy ray irradiation.

Further, in carrying out the method for producing a light-diffusing film of the present invention, it is preferable that the length from the upper end to the lower end of the irradiation light parallelizing unit is in the range of 10 to 1000 mm.

By doing so, it is possible to more efficiently change the irradiation light from the linear light source into parallel light having a predetermined parallelism in the second active energy ray irradiation.

Further, in carrying out the method for producing the light-diffusing film of the present invention, it is preferable that the distance between the upper end of the illumination light parallelizing unit and the lower end of the linear light source is 0 to 1000 mm. The value in the range.

By doing so, it is possible to more efficiently change the irradiation light from the linear light source into parallel light having a predetermined parallelism in the second active energy ray irradiation.

Further, in carrying out the method for producing a light-diffusing film of the present invention, it is preferable that the distance between the lower end of the irradiation light parallelizing unit and the surface of the coating layer is in the range of 0 to 1000 mm.

By doing so, it is possible to more efficiently irradiate the coating layer with parallel light having a predetermined parallelism in the second active energy ray irradiation.

Incidentally, the irradiation light parallelization unit used for the second active energy ray irradiation means a component that increases the parallelism of the irradiation light. More specifically, the illuminating light parallelizing means means a component capable of making the parallelism of the illuminating light to a value of 10 or less.

By doing so, the column structure region as the second structural region can be formed more stably.

1‧‧‧ coating layer

2‧‧‧Technical sheet

10‧‧‧1st structural area (anisotropic light diffusing film)

12‧‧‧ Plate area with high refractive index (high refractive index part)

13‧‧‧ Louver structure

The boundary surface of the 13'‧‧‧ louver structure

14‧‧‧Plate-like region with low refractive index (low refractive index portion)

20‧‧‧2nd structural area (isotropic light diffusing film)

22‧‧‧ pillar

24‧‧‧Parts other than the column (low refractive index part)

30‧‧‧Light diffusing film

50‧‧‧Active energy line (direct light)

60‧‧‧Active energy line (parallel light)

120‧‧‧UV irradiation device

121‧‧‧thermal radiation cut-off filter

122‧‧‧Cold mirror

123‧‧‧ visor

125‧‧‧Wire-shaped ultraviolet light (linear light source)

100‧‧‧Reflective liquid crystal display device

101‧‧‧Polarizer

102‧‧‧ phase difference plate

103‧‧‧Light diffuser

104‧‧‧ glass plate

105‧‧‧ color filter

106‧‧‧LCD

107‧‧‧Mirror reflector

108‧‧‧ glass plate

110‧‧‧Liquid Crystal Unit

200‧‧‧Lighting parallelization components

210‧‧‧Lighting components

210a‧‧‧plate components

210b‧‧‧Cylindrical components

1a to 1b are views for explaining the outline of the louver structure region as the first structural region.

2a to 2b are diagrams for explaining the incident angle dependency and anisotropy in the louver structure region.

Figures 3a-3b are another diagram for explaining the angle dependence of incidence in the area of the louver structure.

Fig. 4 is a view for explaining an opening angle of incident angle diffused light.

5a to 5b are views for explaining the outline of the column structure region as the second structural region.

Figures 6a-6b are diagrams for explaining the angle dependence of incidence and isotropy in the region of the column structure.

7a to 7b are views for explaining the outline of the light diffusion film obtained by the production method of the present invention.

8a to 8b are views for explaining the first active energy ray irradiation step.

9a to 9b are another diagram for explaining the first active energy ray irradiation step.

10a to 10c are diagrams for explaining the second active energy ray irradiation step.

11a to 11b are another diagram for explaining the second active energy ray irradiation step.

12a to 12d are another diagrams for explaining the second active energy ray irradiation step.

13a to 13c are views for explaining the mode of the louver structure region of the first structural region.

14a to 14d are diagrams for explaining the manner of the column structure region of the second structural region.

Fig. 15 is a view for explaining an example of application of a light-diffusing film obtained by the production method of the present invention in a reflective liquid crystal display device.

Fig. 16 is a view for explaining the light diffusion film of Example 1.

17a to 17b are photographs for explaining the cross section of the light diffusion film of Example 1.

Fig. 18 is a view for explaining the light diffusion film of Example 2.

19a to 19b are photographs for explaining the cross section of the light diffusion film of Example 2.

20a to 20k are diagrams for explaining the expansion of the diffused light and the luminance distribution in the light-diffusing film of Reference Example 1.

21a to 21b are photographs for explaining the cross section of the light diffusion film of Reference Example 1.

Fig. 22 is a view for explaining the light diffusion film of Reference Example 2.

23a to 23h are diagrams for explaining the expansion of the diffused light and the luminance distribution in the light-diffusing film of Reference Example 3.

24a to 24g are diagrams for explaining the expansion of the diffused light and the luminance distribution in the light-diffusing film of Reference Example 4.

25a to 25j are diagrams for explaining the expansion of the diffused light and the luminance distribution in the light-diffusing film of Comparative Example 1.

26a to 26k are diagrams for explaining the expansion of the diffused light and the luminance distribution in the light-diffusing film of Comparative Example 2.

27a to 27h are diagrams for explaining the expansion of the diffused light and the luminance distribution in the light-diffusing film of Comparative Example 3.

28a to 28i are diagrams for explaining the expansion of the diffused light and the luminance distribution in the light-diffusing film of Comparative Example 4.

29a to 29b are views for explaining a reflection type liquid crystal device using a conventional light diffusion film.

An embodiment of the present invention provides a method of producing a light-diffusing film, comprising: a first structural region for diffusing anisotropic light of incident light, and an isotropic light for diffusing incident light. a method for producing a light diffusing film in a second structural region, and comprising the following steps (a) to (d): (a) a step of preparing a composition for a light diffusing film; and (b) applying a light diffusing film to the process sheet a step of forming a coating layer with the composition; (c) irradiating the coating layer with the first active energy ray, and forming a plurality of plate shapes having different refractive indices as the first structural region below the coating layer a step in which the region is alternately arranged in any direction along the film surface, and a portion in which the louver structure is not formed is left over the coating layer; (d) the coating layer is further subjected to the second In the region where the louver structure is not formed, a column structure region in which a plurality of pillars having a relatively high refractive index are formed in a region having a relatively low refractive index as a second structural region is formed in a region where the louver structure is not formed, wherein the second active region is formed Energy line irradiation, right Fabric layer is irradiated by light from the collimating assembly irradiation step of irradiating a linear light source.

Hereinafter, the embodiments of the present invention will be specifically described with reference to the drawings, but in order to make the above description easy to understand, first, the basic principle of light diffusion based on the louver structure region and light diffusion based on the column structure region in the light diffusion film. Be explained.

[26] 1. Basic principles

(1) Light diffusion based on louver structure

Fig. 1a shows a plan view (plan view) of a first structural region 10 having only a louver structure region for anisotropic light diffusion of incident light, and Fig. 1b shows a first structural region 10 shown in Fig. 1a along a broken line AA. A cross-sectional view of the first structural region 10 when the cut surface is viewed from the direction of the arrow in the vertical direction.

In the present invention, the anisotropy means that, as shown in FIGS. 2a to 2b, when the light film is diffused, the diffused light is diffused in the plane parallel to the film (diffusion light) The shape of the enlarged shape is different depending on the direction in the plane.

More specifically, for the first structural region 10, mainly, the diffused emitted light is in a plane parallel to the film, and the light is perpendicular to the direction of the louver structure extending in either direction along the film surface. The direction of the diffusion is diffused, so the enlarged shape of the diffused light is substantially elliptical.

Further, as shown in the plan view of Fig. 1a, the first structural region 10 has a plate-like region 12 having a relatively high refractive index and a plate-like region 14 having a relatively low refractive index, which are alternately arranged in parallel along one direction of the film surface. The louver structure 13 is extended.

Further, as shown in the cross-sectional view of Fig. 1b, the plate-like region 12 having a higher refractive index and the plate-like region 14 having a lower refractive index each have a predetermined thickness, and are also alternately parallel in the vertical direction of the first structural region 10. The status of the configuration.

Thereby, as shown in FIGS. 2a to 2b, when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused by the first structural region 10.

That is, as shown in FIG. 1b, the incident angle of the incident light to the first structural region 10 with respect to the boundary surface 13' of the louver structure 13 is a value ranging from parallel to a predetermined angular range, that is, a light diffusion incident angle region. In the case of the internal value, it is estimated that the incident light (52, 54) passes through the plate-like region 12 having a high refractive index in the louver structure region while passing through the film thickness direction, thereby traveling the light on the light-emitting surface side. The direction becomes different.

As a result, when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused by the first structural region 10 (52', 54').

2a to 2b, 6a to 6b, and 7a to 7b, the light diffusion incident angle region is based on the louver structure region in the light diffusion film, the refractive index difference of the pillar structure region, the inclination angle, and the like. The angular area determined for each of the light diffusing films.

Further, in the change of the direction of the incident light inside the high refractive index region 12 in the louver structure, in addition to the step-refractive type in which the direction is changed linearly by total reflection as shown in FIG. 1b In addition to the case, it is also conceivable that the gradient refractive index type is changed in a curved shape.

On the other hand, it is estimated that the incident light 56 when the incident angle of the incident light to the first structural region 10 is outside the light diffusion incident angle region is not diffused by the first structural region 10, but is directly transmitted through the first structural region 10 (56').

According to the above mechanism, the first structural region 10 having the louver structure 13 can exhibit an incident angle dependency in transmission and diffusion of light, for example, as shown in FIGS. 2a to 2b.

Further, as shown in FIGS. 2a to 2b, when the incident angle of the incident light is included in the light diffusion incident angle region in the first structural region, even when the incident angle is different, the incident surface angle can be performed on the light-emitting surface side. Almost the same light spreads.

Here, the relationship between the incident angle of the incident light to the first structural region and the opening angle of the diffused light diffused by the first structural region will be described with reference to FIG. 3a.

That is, FIG. 3a shows a characteristic curve in which the incident angle (°) of the first structural region is taken as the horizontal axis and the opening angle (°) of the diffused light diffused by the first structural region is taken as the vertical axis.

Further, as shown in FIG. 4, the incident angle θ 1 is an angle (°) when the angle at which the first structural region 10 is perpendicularly incident is 0°.

More specifically, as described above, the component of the incident light that contributes to the diffusion of the anisotropic light is mainly a component perpendicular to the orientation of the louver structure extending in either direction along the film surface, so that the present invention The "incident angle θ 1" to the incident light means the incident angle of a component perpendicular to the direction of the louver structure extending in either direction along the film surface. In addition, at this time, the incident angle θ 1 means an angle (°) when the angle of the normal to the incident side surface of the light diffusion film is set to 0°.

Further, the opening angle θ 2 of the diffused light is literally referred to as the opening angle (°) of the diffused light.

Further, the larger the opening angle of the diffused light means that the light incident at the incident angle at this time is more effectively diffused by the first structural region.

On the contrary, the smaller the opening angle of the diffused light, the more the light incident at the incident angle at this time directly passes through the first structural region without being diffused.

Incidentally, a specific measurement method of the opening angle of the diffused light is described in the examples.

That is, it can be understood from the characteristic curve shown in Fig. 3a that, in the case of the first structural region, the degree of transmission and diffusion of light is greatly different depending on the incident angle, and the light can be clearly diffused into the incident angle region and The other angles of incidence are separated.

On the other hand, for a film that does not have an incident angle dependency, as shown in FIG. 3b, the change in the incident angle does not clearly affect the degree of transmission and diffusion of light, and the light diffusion incident angle region cannot be determined.

(2) Light diffusion based on the column structure region

In addition, FIG. 5a shows a plan view (plan view) of the second structure region 20 having only the column structure region and for isotropic light diffusion, and FIG. 5b shows the second structure region 20 shown in FIG. 5a. The broken line AA is cut in the vertical direction, and a cross-sectional view of the second structural region 20 when the cut surface is viewed from the direction of the arrow.

In the present invention, isotropic means that as shown in FIGS. 6a to 6b, when the light film is diffused, the diffused light is diffused in the plane parallel to the film (diffusion light) The expanded shape is a property that does not change due to the direction in the plane.

More specifically, in the second structural region 20, the diffusion of the diffused emitted light is circular in a plane parallel to the film.

Here, as shown in the plan view of Fig. 5a, the second structural region 20 has a pillar structure (22, 24) composed of a pillar 22 having a relatively high refractive index and a region 24 having a relatively low refractive index.

Further, as shown in the cross-sectional view of Fig. 5b, in the vertical direction of the second structural region 20, the pillars 22 having a relatively high refractive index and the regions 24 having a relatively low refractive index have a predetermined width and are alternately arranged. status.

Thereby, as shown in FIGS. 6a to 6b, when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused by the second structural region 20.

That is, as shown in FIG. 5b, the incident angle of the incident light to the second structural region 20 with respect to the boundary surface 23' of the column structure 23 is a value ranging from parallel to a prescribed angular range, that is, a light diffusion incident angle region. In the case of the inner value, it is estimated that the incident light (62, 64) changes direction in the column 22 of the high refractive index in the column structure region, and passes through in the film thickness direction, so that the light on the light-emitting surface side The direction of travel becomes different.

As a result, when the incident angle is within the light diffusion incident angle region, it is estimated that the incident light is diffused by the second structural region 20 (62', 64').

Further, the change in the direction of the incident light in the column 22 having a high refractive index in the columnar structure region is linearly changed by the total reflection as shown in FIG. 5b, and the direction is changed in a zigzag manner. In addition to the case of the step index type, a case of a gradient index type which changes direction in a curved shape can also be considered.

On the other hand, it is estimated that the incident light 66 when the incident angle of the incident light to the second structural region 20 is outside the light diffusion incident angle region is not diffused by the second structural region 20, but directly passes through the second structural region 20 (66'). .

According to the above mechanism, the second structural region 20 including the pillar structure 23 can exhibit an incident angle dependency in light transmission and diffusion, for example, as shown in FIGS. 6a to 6b.

In addition, the relationship between the incident angle of the incident light to the second structural region and the opening angle of the diffused light diffused by the second structural region is the same as that in the first structural region, and therefore will not be described again.

2. Basic composition

Next, the basic configuration of the light diffusion film obtained by the production method of the present invention will be described using a drawing.

As shown in FIGS. 7a to 7b, the light diffusion film 30 is obtained by the manufacturing method of the present invention, and has a louver structure region (first structure region) 10 for diffusing incident light into anisotropic light, and It is preferable that the column structure regions (second structure regions) 20 that diffuse the incident light into the isotropic light include the structural regions in the vertical direction in the film thickness direction.

Therefore, in the light diffusion film obtained by the production method of the present invention, for example, as shown in FIG. 7a, by repeating the incident angle dependency of the first and second structural regions, light diffusion characteristics can be suppressed. The fluctuations give a good angle of incidence dependence.

In addition, as shown in FIG. 7b, the light diffusion film obtained by the production method of the present invention can be effectively and easily expanded by, for example, shifting the incident angle dependency of the first and second structural regions. Light diffuses the angle of incidence.

3. Step (a): Preparation steps of the composition for a light diffusing film

Step (a) is a step of preparing a composition for a predetermined light-diffusing film.

More specifically, it is preferred to mix at least two kinds of polymerizable compounds having different refractive indices, a photopolymerization initiator, and other additives as required.

Further, at the time of mixing, it is possible to directly stir at room temperature, but from the viewpoint of improving uniformity, for example, it is preferred to stir under heating at 40 to 80 °C.

Further, it is also preferred to further add a diluent solvent to achieve a desired viscosity suitable for coating.

Hereinafter, step (a) will be more specifically described.

(1) High refractive index polymerizable compound

(1)-1 type

In the two kinds of polymerizable compounds having different refractive indices, the type of the polymerizable compound having a relatively high refractive index (hereinafter sometimes referred to as the component (A)) is not particularly limited, but it is preferred that the main component contains a plurality of aromatic components. Ring (meth) acrylate.

The reason is that, as a component (A), a polymerizable compound having a polymerization rate of (A) is relatively lower than a refractive index by containing a specific (meth) acrylate (hereinafter sometimes referred to as (B) The polymerization rate of the component) is fast, and the polymerization rate between the components is made to have a predetermined difference, and the copolymerizability of the two components can be effectively reduced.

As a result, when photocuring is performed, the louver structure region and the column structure region composed of the portion derived from the component (A) and the component derived from the component (B) can be efficiently formed.

In addition, it is estimated that the component (A) contains a specific (meth) acrylate, and although it has sufficient compatibility with the component (B) in the monomer phase, in the polymerization process, at a plurality of stages of connection, The compatibility with the component (B) can be lowered to a predetermined range, and the louver structure region and the column structure region can be formed more efficiently.

Further, by containing a specific (meth) acrylate as the component (A), it is possible to increase the portion of the louver structure region and the column structure region from the component (A). The transmittance is adjusted to a value equal to or greater than a predetermined value from the refractive index of the portion derived from the component (B).

Therefore, by containing a specific (meth) acrylate, it is possible to efficiently obtain a louver structure region including a portion having a different refractive index by combining a specific (meth) acrylate with the characteristics of the component (B) to be described later. A light diffusing film in the column structure region.

In addition, the "(meth)acrylate containing a plurality of aromatic rings" means a compound having a plurality of aromatic rings in the ester residue portion of the (meth) acrylate.

Further, "(meth)acrylic" means both acrylic acid and methacrylic acid.

In addition, examples of the (meth) acrylate containing a plurality of aromatic rings as the component (A) include biphenyl (meth)acrylate, naphthyl (meth)acrylate, and (meth)acrylic acid. Oxime ester, benzylphenyl (meth)acrylate, biphenyloxyalkyl (meth)acrylate, naphthyloxyalkyl (meth)acrylate, mercaptooxyalkyl (meth)acrylate A compound such as a base ester, a benzyl phenyloxyalkyl (meth)acrylate or the like, or a compound in which a part of a hydrogen atom on the aromatic ring is substituted with a halogen, an alkyl group, an alkoxy group, a halogenated alkyl group or the like.

In addition, the (meth) acrylate containing a plurality of aromatic rings as the component (A) is preferably a compound containing a biphenyl ring, and more preferably contains a biphenyl compound represented by the following formula (1).

(In the formula (1), R ¹ to R ¹⁰ are each independently, and at least one of R ¹ to R ¹⁰ is a substituent represented by the following formula (2), and the remainder is a hydrogen atom, a hydroxyl group, a carboxyl group, or an alkyl group. , alkoxy, haloalkyl, hydroxyalkyl, carboxyalkyl, and any substituent in the halogen atom)

(In the formula (2), R ¹¹ is a hydrogen atom or a methyl group, the number of carbon atoms n is an integer of 1 to 4, and the number of repetitions m is an integer of 1 to 10)

The reason is that, as a component (A), by including a biphenyl compound having a specific structure, a predetermined difference can be caused in the polymerization rate of the component (A) and the component (B), and the component (A) and (B) can be obtained. The compatibility of the components is lowered to a predetermined range, and the copolymerizability between the two components can be lowered.

Further, the refractive index of the portion derived from the component (A) in the louver structure region and the column structure region can be increased, and the difference in refractive index from the portion derived from the component (B) can be more easily adjusted to a value equal to or greater than a predetermined value.

Further, when R ¹ to R ¹⁰ in the formula (1) contain any one of an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group and a carboxyalkyl group, the number of carbon atoms in the alkyl moiety is preferably A value in the range of 1~4.

The reason is that when the number of carbon atoms exceeds 4, the polymerization rate of the component (A) is lowered, or the refractive index of the portion derived from the component (A) is excessively lowered, and it may be difficult to efficiently form the louver structure. Area and column structure area.

Therefore, when R ¹ to R ¹⁰ in the formula (1) contain any one of an alkyl group, an alkoxy group, a halogenated alkyl group, a hydroxyalkyl group and a carboxyalkyl group, it is preferred to have the carbon number of the alkyl moiety The value in the range of 1 to 3 is more preferably in the range of 1 to 2.

Further, R ¹ to R ¹⁰ in the formula (1) are preferably a halogenated alkyl group or a substituent other than a halogen atom, that is, a substituent which does not contain a halogen.

The reason for this is to prevent the occurrence of dioxin in the case of incinerating a light diffusion film or the like, and it is preferable from the viewpoint of environmental protection.

In the conventional light diffusing film having a louver structure region or the like, when a predetermined louver structure region or the like is obtained, halogen substitution is usually performed in the monomer component for the purpose of increasing the refractive index of the monomer component.

In this regard, when the biphenyl compound represented by the formula (1) is used, a high refractive index can be formed without halogen substitution.

Therefore, when the light-diffusing film obtained by photocuring the composition for a light-diffusion film in the present invention is used, it is possible to exhibit a good incident angle dependency even when halogen is not contained.

Further, any of R ² to R ⁹ in the formula (1) is preferably a substituent represented by the formula (2).

The reason for this is that the position of the substituent represented by the general formula (2) is a position other than R ¹ and R ¹⁰ , whereby the phase (A) components before the photocuring can be effectively prevented from being aligned and crystallized. .

Further, the monomer stage before photocuring is liquid, and it can be apparently uniformly mixed with the component (B) without using a diluent solvent or the like.

Thereby, at the stage of photocuring, the (A) component and the (B) component can be condensed and phase-separated at a fine level, and a light-diffusing film having a louver structure region and a pillar structure region can be obtained more efficiently.

Furthermore, from the same viewpoint, any of R ³ , R ⁵ , R ⁶ and R ⁸ in the formula (1) is preferably a substituent represented by the formula (2).

Further, it is usually preferred that the number m of repeats in the substituent represented by the formula (2) is an integer of from 1 to 10.

The reason for this is that when the number of repetitions m is more than 10, the oxyalkylene chain connecting the polymerization site and the biphenyl ring becomes too long, and polymerization of the component (A) in the polymerization site may be inhibited.

Therefore, the number m of repeats of the substituent represented by the formula (2) is preferably an integer of 1 to 4, and particularly preferably an integer of 1 to 2.

In the same manner, it is preferred that the number of carbon atoms n of the substituent represented by the formula (2) is an integer of from 1 to 4.

In addition, it is preferable to consider that the position of the polymerizable carbon-carbon double bond as the polymerization site is too close to the biphenyl ring and the biphenyl ring is sterically hindered to lower the polymerization rate of the component (A). The number of carbon atoms n of the substituent represented by the formula (2) is an integer of 2 to 4, and is preferably an integer of 2 to 3.

In addition, as a specific example of the biphenyl compound represented by the formula (1), a compound represented by the following formulas (3) to (4) is preferable.

(1)-2 molecular weight

Further, it is preferred that the molecular weight of the component (A) is in the range of 200 to 2,500.

The reason for this is that, by estimating the molecular weight of the component (A) within a predetermined range, the polymerization rate of the component (A) can be further increased, and the copolymerizability of the component (A) and the component (B) can be more effectively reduced.

As a result, when photocuring is performed, the louver structure region and the column structure region composed of the portion derived from the component (A) and the component derived from the component (B) can be formed more efficiently.

In other words, when the molecular weight of the component (A) is less than 200, the polymerization rate is lowered due to steric hindrance, and the polymerization rate of the component (B) is close to that of the component (B). Copolymerization. On the other hand, when the molecular weight of the component (A) is more than 2,500, the difference in molecular weight with the component (B) is small, and the polymerization rate of the component (A) is lowered to become the component (B). When the polymerization rate is close to each other, it is estimated that copolymerization with the component (B) is likely to occur, and as a result, it may be difficult to form the louver structure region and the column structure region efficiently.

Therefore, it is preferable to make the molecular weight of the component (A) in the range of 240 to 1,500, and more preferably in the range of 260 to 1,000.

Incidentally, the molecular weight of the component (A) can be determined from a calculated value obtained from the molecular composition and the atomic weight of the constituent atom, and the weight average molecular weight can also be measured by gel permeation chromatography (GPC).

(1)-3 used alone

Further, the composition for a light-diffusing film of the present invention contains the component (A) as a monomer component of a portion having a relatively high refractive index formed in the louver structure region and the column structure region, but is preferably contained in a single component. (A) ingredient.

The reason for this is that, by such a configuration, it is possible to effectively suppress the fluctuation of the refractive index in the portion derived from the component (A), in other words, the portion having a relatively high refractive index, and is more efficient. A light diffusion film having a louver structure region and a column structure region is obtained.

In other words, when the compatibility of the component (B) with respect to the component (A) is low, for example, when the component (A) is a halogen compound or the like, the other component (A) (for example, a non-halogen compound) may be used in combination. The third component which is compatible with the component (A) and the component (B).

However, at this time, the refractive index of the portion having a relatively high refractive index from the component (A) fluctuates or is likely to be lowered due to the influence of the third component.

As a result, the difference in refractive index between the portion having a relatively low refractive index from the component (B) may become uneven or may be excessively lowered.

Therefore, it is preferred to select a monomer component having a high refractive index which is compatible with the component (B) and use it as a separate component (A).

In addition, when the biphenyl compound represented by the formula (3) which is the component (A) is a low viscosity, it has compatibility with the component (B), and therefore it can be used as a separate (A). Ingredients used.

(1)-4 refractive index

Further, it is preferable that the refractive index of the component (A) is in the range of 1.5 to 1.65.

The reason for this is that, by setting the refractive index of the component (A) to a value within the above range, the difference between the refractive index of the portion derived from the component (A) and the refractive index of the portion derived from the component (B) can be more easily adjusted. A light diffusing film having a louver structure region and a column structure region is more efficiently obtained.

In other words, when the refractive index of the component (A) is less than 1.5, the difference in refractive index from the component (B) is too small, and it may be difficult to obtain a desired incident angle dependency. On the other hand, when the refractive index of the component (A) exceeds 1.65, the difference in refractive index from the component (B) becomes large, but the apparent compatibility with the component (B) may be obtained. The state is also difficult to form.

Therefore, it is preferable to make the refractive index of the component (A) in the range of 1.52 to 1.62, and more preferably in the range of 1.56 to 1.6.

The refractive index of the component (A) is the refractive index of the component (A) before curing by light irradiation.

Further, the refractive index can be measured, for example, in accordance with JIS K0062.

(1)-5 content

In addition, it is preferable that the content of the component (A) in the composition for a light-diffusion film is in the range of 25 to 400 parts by weight based on 100 parts by weight of the component (B) of the polymerizable compound having a relatively low refractive index to be described later. .

The reason is that when the content of the component (A) is less than 25 parts by weight, the ratio of the component (A) to the component (B) is small, and the width of the portion derived from the component (A), in other words, The width of the plate-like region and the width of the pillar are excessively smaller than the width of the portion derived from the component (B), and it is sometimes difficult to obtain a louver structure region and a pillar structure region having a good incident angle dependency. Further, the thickness of the louver structure region and the column structure region in the thickness direction of the light diffusion film is insufficient, and the light diffusibility may not be exhibited. On the other hand, when the content of the component (A) is more than 400 parts by weight, the ratio of the component (A) to the component (B) increases, and the width of the portion derived from the component (A) is derived from (B). The width of the portion of the component is excessively large, and it is sometimes difficult to obtain a louver structure region and a column structure region having a good incident angle dependency. Further, the thickness of the louver structure region and the column structure region in the thickness direction of the light diffusion film is insufficient, and the light diffusibility may not be exhibited.

Therefore, it is more preferable that the content of the component (A) is in the range of 40 to 300 parts by weight based on 100 parts by weight of the component (B), and more preferably in the range of 50 to 200 parts by weight.

(2) Low refractive index polymerizable compound

(2)-1 type

The type of the polymerizable compound having a relatively low refractive index (the component (B)) is not particularly limited, and examples of the main component thereof include urethane (meth) acrylate. a (meth)acrylic polymer having a (meth)acrylonitrile group in the side chain, an organic terpene resin containing a (meth)acrylonitrile group, an unsaturated polyester resin, etc., but is preferably a urethane (methyl group) )Acrylate.

The reason for this is that, when urethane (meth) acrylate is used, not only the difference between the refractive index of the portion derived from the component (A) and the refractive index of the portion derived from the component (B) can be more easily adjusted, but also The fluctuation of the refractive index from the portion of the component (B) is effectively suppressed, and the light diffusion film having the louver structure region and the pillar structure region is more efficiently obtained.

Therefore, urethane (meth) acrylate which is a component (B) will be mainly described below.

In addition, (meth)acrylate means both an acrylate and a methacrylate.

First, urethane (meth) acrylate is formed of (B1) a compound containing at least two isocyanate groups, (B2) a polyol compound, and (B3) a hydroxyalkyl (meth) acrylate, wherein (B2) is preferably The diol compound is preferably a polyalkylene glycol.

Incidentally, the component (B) further contains an oligomer having a repeating unit of a urethane bond.

In addition, examples of the compound containing at least two isocyanate groups as the component (B1) include, for example, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, and 1,3-benzenedimethylene diisocyanate. , an aromatic polyisocyanate such as 4-benzene dimethylene diisocyanate, an aliphatic polyisocyanate such as hexamethylene diisocyanate, an alicyclic polycondensation such as isophorone diisocyanate (IPDI) or hydrogenated diphenylmethane diisocyanate; Isocyanates, and such biuret, isocyanurate, and reactants as low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil An adduct (for example, a benzene dimethylene diisocyanate trifunctional adduct) or the like.

Further, in the above, it is preferably an alicyclic polyisocyanate.

The reason for this is that when the alicyclic polyisocyanate is used, it is easier to set a difference in the reaction rate of each isocyanate group than the aliphatic polyisocyanate due to the spatial conformation or the like.

Therefore, it is possible to prevent the component (B1) from reacting only with the component (B2), or the component (B1) to react only with the component (B3), and to reliably react the component (B1) with the component (B2) and the component (B3). Prevent the generation of excess by-products.

As a result, it is possible to effectively suppress the fluctuation of the refractive index of the portion derived from the component (B) in the louver structure region and the column structure region, that is, the low refractive index portion.

In addition, when it is an alicyclic polyisocyanate, the compatibility of the obtained (B) component and (A) component can be reduced to a predetermined range, and the louver structure area can be formed more efficiently than an aromatic polyisocyanate. And the column structure area.

Further, when the alicyclic polyisocyanate is used, the refractive index of the obtained component (B) can be made smaller than that of the aromatic polyisocyanate, so that the difference in refractive index from the component (A) is increased, and the efficiency is further improved. The louver structure region and the column structure region excellent in incident angle dependency are formed in the ground.

Further, in such an alicyclic polyisocyanate, an alicyclic diisocyanate containing only two isocyanate groups is preferable.

The reason for this is that when the alicyclic diisocyanate is used, it is possible to quantitatively react with the component (B2) and the component (B3) to obtain a single component (B).

As such an alicyclic diisocyanate, isophorone diisocyanate (IPDI) is preferable.

The reason for this is that an effective difference can be provided for the reactivity of two isocyanate groups.

Further, among the components forming the urethane (meth) acrylate, the polyalkylene glycol as the component (B2) may, for example, be polyethylene glycol, polypropylene glycol, polytetramethylene glycol or polyhexanediol. Etc., among them, it is preferably polypropylene glycol.

The reason for this is that if the polypropylene glycol is used, the viscosity is low, so that solventless treatment can be performed.

In addition, when the component (B) is cured, the component (B) is a good soft segment in the cured product, and the handleability and mountability of the light-diffusing film can be effectively improved.

Incidentally, the weight average molecular weight of the component (B) can be mainly adjusted by the weight average molecular weight of the component (B2). Here, the weight average molecular weight of the component (B2) is usually from 2,300 to 19,500, preferably from 4,300 to 14,300, and more preferably from 6,300 to 1,230.

Further, among the components forming the urethane (meth) acrylate, as the (B3) component, that is, the hydroxyalkyl (meth)acrylate, for example, 2-hydroxyethyl (meth)acrylate or (methyl) ) 2-hydroxypropyl acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxy butyl (meth) acrylate Ester and the like.

Further, from the viewpoint of lowering the polymerization rate of the obtained urethane (meth) acrylate and forming a predetermined louver structure region and column structure region more efficiently, it is more preferably a hydroxyalkyl methacrylate, more preferably 2-hydroxyethyl methacrylate.

Further, the synthesis of urethane (meth) acrylate by the components (B1) to (B3) can be carried out according to a conventional method.

In this case, the ratio of the components (B1) to (B3) is preferably a ratio of (B1) component: (B2) component: (B3) component = 1 to 5: 1:1 to 5 in terms of molar ratio.

The reason for this is that it is possible to efficiently synthesize one of the isocyanate groups of the component (B1) and the two hydroxyl groups of the component (B2) by the above-mentioned mixing ratio, and to bond and bond the (B3) component. A urethane (meth) acrylate in which a hydroxyl group is reacted with another isocyanate group of each of the two (B1) components and bonded.

Therefore, it is preferable to make the ratio of the components (B1) to (B3) in the molar ratio (B1). Ingredients: (B2) Component: (B3) Component = 1 to 3: 1:1 to 3 ratio, more preferably 2:1:2 ratio.

2)-2 weight average molecular weight

Further, it is preferred that the weight average molecular weight of the component (B) is in the range of from 3,000 to 20,000.

The reason for this is that when the weight average molecular weight of the component (B) is within a predetermined range, the polymerization rate of the component (A) and the component (B) can be made to have a predetermined difference, and the copolymerizability of the two components can be effectively reduced.

As a result, when photocuring is performed, the louver structure region and the column structure region composed of the portion derived from the component (A) and the component derived from the component (B) can be efficiently formed.

In other words, when the weight average molecular weight of the component (B) is less than 3,000, the polymerization rate of the component (B) is increased, and the polymerization rate of the component (A) is close to that of the component (A). As a result of the copolymerization, it is sometimes difficult to form the louver structure region and the column structure region efficiently. On the other hand, when the weight average molecular weight of the component (B) is more than 20,000, it may be difficult to form the louver structure region and the column structure region composed of the components from the component (A) and the component (B), or The compatibility of the component (A) was excessively lowered and analyzed in the coating stage (A).

Therefore, it is preferable to make the weight average molecular weight of the component (B) in the range of 5,000 to 15,000, and more preferably in the range of 7,000 to 13,000.

Incidentally, the weight average molecular weight of the component (B) can be measured by gel permeation chromatography ((GPC).

(2)-3 used alone

Further, the component (B) may be used in combination of two or more kinds having different molecular structures and weight average molecular weights. However, from the viewpoint of suppressing the fluctuation of the refractive index of the portion derived from the component (B) in the louver structure region and the column structure region, Use only one type.

That is, when a plurality of (B) components are used, the refractive index in the portion having a relatively low refractive index from the component (B) fluctuates or becomes high, and sometimes the refractive index of the portion having a relatively high refractive index from the component (A) The rate difference becomes uneven or excessively reduced.

(2)-4 refractive index

Further, it is preferable that the refractive index of the component (B) is in the range of 1.4 to 1.55.

The reason for this is that, by setting the refractive index of the component (B) to a value within the above range, the difference between the refractive index of the portion derived from the component (A) and the refractive index of the portion derived from the component (B) can be more easily adjusted. A light diffusing film having a louver structure region and a column structure region is more efficiently obtained.

In other words, when the refractive index of the component (B) is less than 1.4, the difference in refractive index from the component (A) is large, but the compatibility with the component (A) is extremely deteriorated, and louvers may not be formed. Structure area and column structure area. On the other hand, when the refractive index of the component (B) exceeds 1.55, the difference in refractive index from the component (A) becomes too small, and it may be difficult to obtain a desired incident angle dependency.

Therefore, it is preferable to make the refractive index of the component (B) in the range of 1.45 to 1.54, and more preferably in the range of 1.46 to 1.52.

The refractive index of the component (B) is the refractive index of the component (B) before curing by light irradiation.

Further, the refractive index can be measured, for example, in accordance with JIS K0062.

Moreover, it is preferable that the difference between the refractive index of the component (A) and the refractive index of the component (B) is 0.01 or more.

The reason for this is that by setting the difference in refractive index to a value within a predetermined range, it is possible to obtain light having a more favorable incident angle dependency and a wider light diffusion incident angle region in light transmission and diffusion. Diffusion film.

In other words, when the difference in refractive index is less than 0.01, the angle of total reflection of incident light in the louver structure region and the column structure region is narrowed, so that the opening angle of light diffusion may be excessively narrow. On the other hand, when the difference in refractive index is an excessively large time value, the compatibility between the component (A) and the component (B) is excessively deteriorated, and the louver structure region and the column structure region may not be formed.

Therefore, it is preferable that the difference between the refractive index of the component (A) and the refractive index of the component (B) is in the range of 0.05 to 0.5, and more preferably in the range of 0.1 to 0.2.

In addition, the refractive index of the (A) component and (B) component here is the refractive index of (A) component and (B) component before hardening by light irradiation.

(2)-5 content

In addition, the content of the component (B) in the composition for a light-diffusing film is preferably in the range of 10 to 80% by weight based on 100% by weight of the total amount of the composition for a light-diffusing film.

The reason is that when the content of the component (B) is less than 10% by weight, the ratio of the component (B) to the component (A) is small, and the width of the portion derived from the component (B) is derived from The width of the portion of the component (A) is excessively small, and it may be difficult to obtain a louver structure region and a column structure region having a good incident angle dependency. Further, the thickness of the louver structure region and the column structure region in the thickness direction of the light diffusion film may be insufficient. On the other hand, when the content of the component (B) is more than 80% by weight, the ratio of the component (B) to the component (A) increases, and the width of the portion derived from the component (B) is derived from (A). The width of the portion of the component is excessively large, and it is sometimes difficult to obtain a louver structure region and a column structure region having a good incident angle dependency. Further, the thickness of the louver structure region and the column structure region in the thickness direction of the light diffusion film may be insufficient.

Therefore, it is preferable that the content of the component (B) is in the range of 20 to 70% by weight based on 100% by weight of the total amount of the composition for a light-diffusing film, and more preferably in the range of 30 to 60% by weight. value.

(3) Photopolymerization initiator

Further, in the composition for a light-diffusing film of the present invention, it is preferred to contain a photopolymerization initiator as the component (C) as required.

The reason for this is that when the active energy ray is irradiated to the composition for a light-diffusion film by containing a photopolymerization initiator, the louver structure region and the column structure region can be efficiently formed.

Here, the photopolymerization initiator refers to a compound which generates a radical species by irradiation with an active energy ray such as ultraviolet rays.

Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, and acetophenone. , dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl 1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-propan-1-one , 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)one, benzophenone, p-phenylbenzophenone, 4,4-diethylaminobiphenyl Ketone, dichlorobenzophenone, 2-methyl hydrazine, 2-ethyl hydrazine, 2-tert-butyl hydrazine, 2-amino hydrazine, 2-methyl thioxanthone, 2-ethyl thiophene Tons of ketone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzoin dimethyl ketal, acetophenone dimethyl ketal, For p-dimethylamine benzoate or oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propane], one of them may be used singly or in combination. Two or more types are used in combination.

In addition, the content in the case where the photopolymerization initiator is contained is preferably in the range of 0.2 to 20 parts by weight based on 100 parts by weight of the total amount of the components (A) and (B), and is preferably 0.5 to 0.5 part by weight. A value in the range of 15 parts by weight is more preferably in the range of 1 to 10 parts by weight.

(4) Other additives

Further, additives other than the above compounds may be appropriately added insofar as the effects of the present invention are not impaired.

Examples of such an additive include an antioxidant, an ultraviolet absorber, an antistatic agent, a polymerization accelerator, a polymerization inhibitor, an infrared absorber, a plasticizer, a diluent solvent, and a leveling agent.

In addition, the content of such an additive is usually preferably in the range of 0.01 to 5 parts by weight, preferably 0.02 to 3 parts by weight, based on 100 parts by weight of the total amount of the components (A) and (B). The value within the range is more preferably in the range of 0.05 to 2 parts by weight.

4. Step (b): Coating step

As shown in FIG. 8a, the step (b) is a step of coating the composition for a light-diffusing film prepared for the process sheet 2 to form the coating layer 1.

As the process sheet, any of a plastic film and paper can be used.

In addition, examples of the plastic film include a polyester film such as a polyethylene terephthalate film, a polyolefin film such as a polyethylene film or a polypropylene film, and a cellulose film such as a triacetyl cellulose film. And a polyimide film or the like.

Further, examples of the paper include cellophane, coated paper, and laminated paper.

In addition, in consideration of a step to be described later, a film excellent in dimensional stability to heat and active energy rays is preferably used as the process sheet 2.

As such a film, a polyester film, a polyolefin film, and a polyimide film are preferable among the plastic film.

Further, after photocuring the process sheet, in order to facilitate the peeling of the obtained light diffusion film from the process sheet, it is preferred to provide a release layer on the coated surface side of the light diffusion film composition in the process sheet.

The release layer can be formed using a conventionally known release agent such as an organic ruthenium release agent, a fluorine release agent, an alkyd release agent, or an olefin release agent.

It should be noted that the thickness of the process sheet is usually preferably in the range of 25 to 200 μm .

Further, as a method of applying the light-diffusing film composition to the process sheet, for example, a doctor blade coating method, a roll coating method, a bar coating method, a blade coating method, a die coating method, and a gravure coating method can be used. A well-known method is carried out.

In this case, the thickness of the coating layer is preferably in the range of 100 to 700 μm .

5. Step (c): First active energy ray irradiation step

Step (c): irradiating the coating layer with the first active energy ray, and forming a plurality of plate-like regions having different refractive indices as the first structural region in the lower portion of the coating layer, alternating in either direction along the film surface The step of arranging the louver structure region and leaving a region where the louver structure is not formed in the upper portion of the coating layer.

That is, as shown in FIG. 8b, for the coating layer 1 formed on the process sheet 2, the active energy ray 50 composed of direct light controlled only by the irradiation angle is irradiated.

More specifically, for example, as shown in FIG. 9a, the ultraviolet ray irradiation device 120 is provided with a condensing mirror 122 for concentrating the linear ultraviolet ray lamp 125 (for example, when it is a commercially available product) The heat radiation cut filter 121 and the light shielding plate 123 are disposed in EYE GRAPHICS Co., Ltd., ECS-4011GX, etc., and the active energy ray 50 composed of direct light controlled only by the irradiation angle is taken out and formed on the process sheet. The coating layer 1 on 2 is irradiated.

In the linear ultraviolet lamp, the direction parallel to the longitudinal direction of the process sheet 2 having the coating layer 1 is usually used as a reference (0°) to be in the range of -80 to 80°. The value in the range is preferably in the range of -50 to 50°, and is preferably set to a value in the range of -30 to 30°.

Here, the reason why the linear light source is used is that the plate-shaped regions having different refractive indexes can be efficiently and stably produced alternately and arranged in parallel with respect to the film thickness direction at a constant inclination angle. The louver structure region is formed as the first structural region.

More specifically, by using a linear light source, it is possible to illuminate light that is substantially parallel when viewed from a direction perpendicular to the axial direction of the linear light source when viewed from the axial direction of the linear light source.

In this case, as shown in FIG. 9b, the irradiation angle of the irradiation light is preferably such that the irradiation angle θ 3 when the angle of the normal to the surface of the coating layer 1 is 0° is -80 to 80°. The value within the range.

The reason for this is that when the irradiation angle is a value outside the range of -80 to 80°, the influence of reflection or the like on the surface of the coating layer 1 becomes large, and it may be difficult to form a sufficient louver structure region.

Further, the irradiation angle θ 3 is preferably a width (irradiation angle width) θ 3' of 1 to 80°.

The reason is that when the irradiation angle width θ 3 ′ is less than 1°, the interval between the louver structure regions is too narrow, and it may be difficult to obtain a desired first structure region. On the other hand, when the irradiation angle width θ 3 ' is a value exceeding 80°, the irradiation light is excessively dispersed, and it may be difficult to form the louver structure region.

Accordingly, more appropriate to make the irradiation angle [theta] 3 of the irradiation angle θ 3 'value in the range of 2 ~ 45 °, more appropriate value in the range of 5 ~ 20 ° of.

Further, examples of the irradiation light include ultraviolet rays, electron beams, and the like, and it is preferred to use ultraviolet rays.

The reason for this is that, in the case of an electron beam, the polymerization rate is very fast, and therefore, the components (A) and (B) are not sufficiently separated during the polymerization, and it may be difficult to form a louver structure region. On the other hand, when compared with visible light or the like, the ultraviolet curable resin which is cured by irradiation and the photopolymerization initiator which can be used are abundant in ultraviolet rays, so that the selection of the component (A) and the component (B) can be expanded. range.

Further, as the irradiation condition of the ultraviolet ray, a value in which the peak illuminance on the surface of the coating layer is in the range of 0.01 to 50 mW/cm ² is preferable.

The reason is that when the peak illuminance is less than 0.01 mW/cm ² , the region in which the louver structure is not formed can be sufficiently formed, but it may be difficult to form the louver structure region clearly. On the other hand, when the peak illuminance is a value exceeding 50 mW/cm ² , the components (A) and (B) are cured before phase separation, and it is sometimes difficult to form the louver structure region clearly.

Therefore, it is preferable that the peak illuminance of the ultraviolet ray on the surface of the coating layer is a value in the range of 0.05 to 20 mW/cm ² . More preferably, it is a value in the range of 0.1 to 10 mW/cm ² .

Incidentally, the term "peak illuminance" as used herein refers to a measured value of a portion where the active energy ray that is irradiated onto the surface of the coating layer shows a maximum value.

Further, it is preferable that the coating layer formed on the process sheet is moved at a speed of 0.1 to 10 m/min to be irradiated with ultraviolet rays irradiated by an ultraviolet irradiation device.

The reason for this is that when the speed is less than 0.1 m/min, the mass productivity may be excessively lowered. On the other hand, when the above-mentioned speed is a value exceeding 10 m/min, the curing of the coating layer, in other words, the formation of the louver structure region is faster, the incident angle of the ultraviolet ray to the coating layer is changed, and sometimes the louver structure region is The formation becomes insufficient.

Therefore, it is preferred that the coating layer formed on the process sheet is moved at a speed in the range of 0.2 to 5 m/min to be irradiated with ultraviolet rays irradiated by the ultraviolet irradiation device, preferably 0.5 to 3 m/min. The speed within the range passes.

6. Step (d): second active energy ray irradiation step

In the step (d), the coating layer is further subjected to a second active energy ray irradiation, and a plurality of pillars having a relatively high refractive index as a second structural region are formed in a region where the refractive index is relatively low in a region where the louver structure is not formed. a column structure region in which the second active energy ray is irradiated, and the coating layer is irradiated with the light source from the linear light source by the illuminating light parallelizing unit The step of illuminating the light.

That is, for example, as shown in FIGS. 10a to 10b, the irradiation light parallelizing unit 200 (200a, 200b) is used to form the irradiation light 50 from the linear light source 125 into parallel light 60 having a high parallelism, and the pair is formed. The coating layer (10, 10') on the process sheet 2 is irradiated.

Further, when the parallel light is irradiated, the coating layer may be directly irradiated. However, it is preferable to form a release film on the surface of the exposed coating layer and irradiate it through the release film.

In this case, as the release film, a process sheet having ultraviolet light transmittance can be appropriately selected from the above-described process sheets which are described as process sheets.

Here, as the direct light generated by the linear light source irradiated as the first active energy ray for forming the louver structure region, substantially no direction in the direction of the light perpendicular to the axial direction of the linear light source The enlargement is substantially parallel, but in the direction parallel to the axial direction of the linear light source, the directions of the light are not uniform but random.

On the other hand, as the irradiation light from the linear light source irradiated by the irradiation light parallelizing unit as the second active energy ray for forming the column structure region, the direction of the emitted light is viewed from an arbitrary direction. All are substantially parallel light that is not enlarged, that is, parallel light.

Incidentally, as shown in FIG. 10c, in the direct light generated by the linear light source 125, the direct light generated by the linear light source 125 is parallel to the axial direction of the linear light source 125 which is random in the direction of light. In the above, for example, by using the light-shielding unit 210 such as the plate-like unit 210a and the cylindrical unit 210b, the direction of light is unified, and the direct light generated by the linear light source 125 can be converted into parallel light.

More specifically, among the direct light generated by the linear light source 125, light having a low degree of parallelism with respect to the light-shielding component 210 such as the plate-like assembly 210a or the cylindrical component 210b is in contact with and absorbed.

Therefore, only the flat portion of the light-shielding component 210 such as the plate-like assembly 210a and the tubular assembly 210b is flat. The light having a high degree of motion, i.e., the parallel light, is parallelized by the illumination light 200, and as a result, the direct light generated by the linear light source 125 is converted into parallel light by the illumination light parallelization unit 200.

Further, the irradiation light parallelizing unit used in the present invention is not particularly limited as long as it can convert the irradiation light from the linear light source into parallel light having a high degree of parallelism, but it is preferably as shown in FIG. 10a. The plate-like unit 210a is configured to illuminate the light parallelizing unit 200a in which the plurality of plate-like members 210a are arranged in parallel when viewed from above the film.

The reason for this is that, in the case of such an irradiation light parallelizing unit 200a, the irradiation light from the linear light source 125 can be easily converted into parallel light having a predetermined parallelism in the second active energy ray irradiation.

That is, by simply arranging the plurality of plate-like members 210a in parallel, it is possible to easily convert the direct light generated by the linear light source 125 into parallel light.

Further, as shown in Fig. 11a, it is preferable that the interval L1 of the plurality of plate-like members 210a is a value within a range of 1 to 100 mm.

The reason for this is that the distance L1 between the plurality of plate-like members 210a is set to a value within the above range, whereby the irradiation light from the linear light source 125 can be more efficiently converted into having the second active energy ray irradiation. Parallel light of the specified parallelism.

In other words, when the interval L1 of the plurality of plate-like members 210a is a value less than 1 mm, the number of the plate-like members 210a is excessively increased, and the irradiation light from the linear light source 125 is sometimes prevented from reaching the coating layer (10, 10). '). On the other hand, when the interval L1 of the plurality of plate-like members 210a is a value exceeding 100 mm, the action of unifying the traveling direction of the irradiation light from the linear light source 125 is excessively lowered, and it may be difficult to have a predetermined parallelism. Parallel light is transformed.

Therefore, it is preferable to set the interval L1 of the plurality of plate-like members 210a to a value in the range of 5 to 75 mm, and more preferably in the range of 10 to 50 mm.

It should be noted that FIG. 11a is an illumination light parallelization assembly shown in FIG. 10a viewed from above the film. Top view of 200a (plan view).

Further, the width L2 of the plate-like member 210a is not particularly limited, but is usually preferably in the range of 10 to 1000 mm, and more preferably in the range of 50 to 500 mm.

Incidentally, the diameter of the linear light source 125 in the axial direction is usually preferably a value in the range of 5 to 100 mm.

Further, the thickness of the plate-like member 210a is not particularly limited, and is usually preferably in the range of 0.1 to 5 mm, and more preferably in the range of 0.5 to 2 mm.

Further, the material of the plate-like member 210a is not particularly limited as long as it can absorb light having a low degree of parallelism with respect to the plate-like member 210a. For example, aluminum plating (ALSTAR) which has been subjected to heat-resistant black coating can be used. Steel plate, etc.

Further, it is preferable that the illuminating light parallelizing unit 200a is disposed in a direction in which the plate-like assembly intersects the axis of the linear light source.

Further, as shown in Fig. 11a, it is preferable that the direction in which the plate-like unit 210a and the linear light source 125 are orthogonal to each other when viewed from above the film, that is, the direction in which θ 4 = 90° is arranged to be parallel to the irradiation light. Component 200a.

The reason for this is that by arranging the irradiation light parallelizing unit 200a in this manner, it is possible to more efficiently convert the irradiation light from the linear light source 125 into parallel light having a predetermined parallelism in the second active energy ray irradiation.

In other words, by arranging the illumination light parallelizing unit 200a in this manner, in the direct light generated by the linear light source 125, it is possible to more efficiently in a direction parallel to the axial direction of the linear light source 125 in which the light direction is random. Unify the direction of light.

Further, as the irradiation light parallelizing unit used in the present invention, it is preferable that the irradiation light parallelizing unit 200b is an aggregate of the plurality of cylindrical members 210b as shown in Fig. 10b.

The reason for this is that, in the case of such an irradiation light parallelizing unit 200b, it is possible to more easily convert the irradiation light from the linear light source 125 into parallel light having a predetermined parallelism in the second active energy ray irradiation.

In other words, the traveling direction of the irradiation light generated by the linear light source 125 is substantially uniform in a direction substantially perpendicular to the axial direction of the linear light source 125, but it may be slightly enlarged.

In this regard, when such an illumination light parallelizing unit 200b is used, even if the direction of light can be unified in a direction perpendicular to the axial direction of the linear light source 125, direct light generated by the linear light source 125 can be generated. Converted to parallel light with a higher degree of parallelism.

Further, as shown in Figs. 12a to 12d, it is preferable that the cylindrical members 210b (210b', 210b", 210b", 210b"" have a maximum diameter L3 (L3', L3", L3' ", L3"") is a value in the range of 1 to 100 mm.

The reason for this is that, by setting the maximum diameter L3 of the tubular member 210b to a value within the above range, the irradiation light from the linear light source 125 can be more efficiently converted into the regulation in the second active energy ray irradiation. Parallel light of parallelism.

That is, when the maximum diameter L3 of the tubular member 210b is a value less than 1 mm, the number of the tubular components 210b is excessively increased, and the irradiation light from the linear light source 125 is sometimes prevented from reaching the coating layer (10, 10'). ). On the other hand, when the maximum diameter L3 of the tubular member 210b is a value exceeding 100 mm, the action of unifying the traveling direction of the irradiation light from the linear light source 125 is excessively lowered, and it may be difficult to parallel to a predetermined parallelism. Light changes.

Therefore, it is preferable that the maximum diameter L3 of the cylindrical member 210b is in the range of 5 to 75 mm, and more preferably in the range of 10 to 50 mm.

Incidentally, Fig. 12a is a plan view (plan view) of the illuminating light parallelizing unit 200b shown in Fig. 10b viewed from above the film.

In addition, FIG. 12a shows a case (210b') in which the planar shape of the opening portion of the tubular member 210b is a quadrangle when the irradiation light parallelizing unit 200b is viewed from above the film.

On the other hand, Figs. 12b to 12d show the case where the planar shape of the opening portion of the cylindrical member 210b is hexagonal, triangular, and circular when the irradiation light parallelizing unit 200b is viewed from above the film (210b", 210b' ", 210b"").

In addition, from the viewpoint that the performance of the transition to the parallel light does not cause a difference in the azimuthal direction, the planar shape of the opening portion of the cylindrical member 210b is preferably a circular shape as shown in Fig. 12d, but the aperture ratio is sometimes lowered. The problem.

Therefore, it is preferable that the performance of the transition toward the parallel light is small in the azimuthal direction, and the hexagonal shape as shown in Fig. 12b can be increased.

Further, the width L4 of the aggregate of the plurality of cylindrical members 210b is not particularly limited, but is usually preferably in the range of 10 to 1000 mm, and more preferably in the range of 50 to 500 mm.

Further, the thickness of the partition wall of the tubular portion of the tubular member 210b is not particularly limited, and is usually preferably in the range of 0.1 to 5 mm, and more preferably in the range of 0.5 to 2 mm.

Further, the material of the tubular member 210b is not particularly limited, and for example, an aluminum-plated steel sheet or the like which has been subjected to heat-resistant black coating can be used.

In addition, regardless of the manner of illuminating the light parallelizing component, as shown in FIG. 11b, it is preferable that the length L5 of the upper end to the lower end of the illuminating light parallelizing component in the illuminating light parallelizing unit 200 is in the range of 10 to 1000 mm. value.

The reason for this is that the length L5 from the upper end to the lower end of the irradiation light parallelizing unit is a value in the range of 10 to 1000 mm, whereby the second active energy ray irradiation can further efficiently obtain the light source from the linear light source. The illumination light of 125 is converted into parallel light having a prescribed parallelism.

In other words, when the length L5 is less than 10 mm, the irradiation light from the linear light source 125 is easily transmitted directly through the inside of the irradiation light parallelizing unit 200, and the traveling direction of the irradiation light from the linear light source 125 is unified. Too much reduction, sometimes it is difficult to make a transition to parallel light with a specified parallelism. On the other hand, when the length L5 is a value exceeding 1000 mm, the distance between the linear light source 125 and the coating layer (10, 10') is excessively large, and it may be difficult to apply the coating layer (10, 10'). The surface is fully illuminated.

Therefore, it is more preferable that the length L5 of the upper end to the lower end of the illumination light parallelizing unit is in the range of 20 to 750 mm, and it is preferably a value in the range of 50 to 500 mm.

Incidentally, Fig. 11b is a side view of the illumination light parallelizing unit 200a shown in Fig. 10a as seen from the axial direction of the linear light source 125.

In addition, regardless of the manner of illuminating the light parallelizing component, as shown in FIG. 11b, it is preferable that the distance L6 between the upper end of the illuminating light parallelizing unit 200 and the lower end of the linear light source 125 is in the range of 0 to 1000 mm. value.

The reason is that, by setting the distance L6 to a value in the range of 0 to 1000 mm, the irradiation light from the linear light source 125 can be more efficiently converted into a predetermined one in the second active energy ray irradiation. Parallel light of parallelism.

In other words, when the distance L6 is a value exceeding 1000 mm, the expansion of the irradiation light in the direction parallel to the axial direction of the linear light source 125 is excessively large, and even when the light is parallelized by the irradiation unit 200, it may be difficult to obtain. Specified parallel light.

Further, the distance between the linear light source 125 and the coating layer (10, 10') is excessively large, and it may be difficult to obtain sufficient illuminance on the surface of the coating layer (10, 10').

On the other hand, when the distance L6 is an excessively small value, the plate-like assembly excessively absorbs heat energy from the linear light source, and countermeasures for preventing deterioration of the irradiation light parallelizing unit due to heat may be required.

Therefore, it is preferable that the distance L6 between the upper end of the irradiation light parallelizing unit 200 and the lower end of the linear light source 125 is in the range of 0.1 to 500 mm, and more preferably in the range of 1 to 100 mm.

In addition, regardless of the manner of illuminating the light parallelizing component, as shown in FIG. 11b, it is preferable that the distance L7 between the lower end of the illumination light parallelizing unit 200 and the surface of the coating layer (10, 10') is 0~ A value in the range of 1000 mm.

The reason for this is that, by setting the distance L7 to a value in the range of 0 to 1000 mm, it is possible to more efficiently irradiate the coating layer (10, 10') with a predetermined parallel in the second active energy ray irradiation. Parallel light of degree.

In other words, when the distance L7 is a value exceeding 1000 mm, the irradiation light that is unified to a predetermined parallel degree may excessively expand before reaching the coating layer (10, 10').

Further, the distance between the linear light source 125 and the coating layer (10, 10') is excessively increased, and it may be difficult to obtain sufficient illuminance on the surface of the coating layer (10, 10').

On the other hand, if the above-described distance L7 is an excessively small value, the lower end of the irradiation light parallelizing unit may come into contact with the surface of the coating layer due to slight vibration at the time of irradiation.

Therefore, it is preferable that the distance L7 between the lower end of the irradiation light parallelizing unit 200 and the surface of the coating layer (10, 10') is in the range of 0.1 to 500 mm, more preferably in the range of 1 to 100 mm. value.

In addition, the illuminating light parallelizing means means a component that makes the illuminating light into parallel light. Specifically, it means a component in which the irradiation light is parallel light having a parallelism of 10 or less.

By setting the parallelism of the irradiation light to a value within the above range, it is possible to efficiently and stably form a column structure region as a second structural region in which a plurality of pillars are formed at a constant inclination angle with respect to the film thickness direction. .

When the parallelism is a value exceeding 10°, the column structure region may not be formed.

Therefore, the irradiation light parallelizing means is preferably a component which makes the parallelism of the irradiation light 5 or less, and is more preferably a component which makes the parallelism of the irradiation light 2 or less.

Further, examples of the irradiation light include ultraviolet rays, electron beams, and the like. However, it is preferable to use ultraviolet rays for the same reason as in the first active energy ray irradiation step.

Further, as the irradiation condition of the ultraviolet rays, the peak illuminance on the surface of the coating layer is preferably in the range of 0.01 to 30 mW/cm ² .

The reason is that when the peak illuminance is less than 0.01 mW/cm ² , it may be difficult to form the column structure region clearly. On the other hand, when the peak illuminance is a value exceeding 30 mW/cm ² , the components (A) and (B) are cured before phase separation, and it is sometimes difficult to form the column structure region clearly.

Therefore, it is preferable that the peak illuminance of the ultraviolet ray on the surface of the coating layer is a value in the range of 0.05 to 20 mW/cm ² . More preferably, it is a value in the range of 0.1 to 10 mW/cm ² .

Further, the moving speed of the coating layer and the irradiation angle of the irradiation light may be the same as those of the first active energy ray irradiation step.

Further, in order to increase the total amount of light to be sufficiently cured by the coating layer, it is preferable to further irradiate the active energy ray differently from the first and second active energy ray irradiation.

Since the coating layer is sufficiently cured, the active energy ray at this time is preferably non-parallel light or the like, but is a light having a random traveling direction.

Further, the light-diffusing film after the photo-curing step is finally brought into a usable state by peeling off the process sheet.

7. Light diffusing film

(1) The first structural area

The light diffusion film obtained by the production method of the present invention is characterized in that it is used for The first structural region in which the anisotropic light is diffused by the projecting light has a plurality of plate-like regions having different refractive indices, that is, a plate-like region (high refractive index portion) having a relatively high refractive index and a plate-like region having a relatively low refractive index ( The low refractive index portion is a louver structure region that is alternately arranged in parallel along any direction of the film surface.

Hereinafter, the first structural region will be specifically described.

(1)-1 refractive index

In the first structural region, the difference in refractive index between the plate-like regions having different refractive indices, that is, the difference between the refractive index of the high refractive index portion and the refractive index of the low refractive index portion is preferably 0.01 or more.

The reason for this is that by setting the difference in refractive index to a value of 0.01 or more, incident light can be stably reflected in the louver structure region as the first structural region, and the incident angle dependency from the first structural region can be further improved. And the opening angle of the diffused light.

More specifically, when the difference in refractive index is less than 0.01, the angle of total reflection of incident light in the louver structure becomes narrow, and the incident angle dependency may be excessively lowered, or the opening angle of the diffused light may be Excessively narrowing.

Therefore, it is preferable that the difference in refractive index between the plate-like regions having different refractive indices in the first structural region is 0.05 or more, and more preferably 0.1 or more.

In addition, it is preferable that the difference between the refractive index of the high refractive index portion and the refractive index of the low refractive index portion is larger, but from the viewpoint of selecting a material capable of forming the louver structure region, it is considered that the upper limit is about 0.3.

Further, in the first structural region, it is preferable that the refractive index of the plate-like region (high refractive index portion) having a relatively high refractive index is in the range of 1.5 to 1.7.

The reason is that if the refractive index of the high refractive index portion is less than 1.5, the difference from the low refractive index portion is too small, and it may be difficult to obtain a desired louver structure region.

On the other hand, when the refractive index of the high refractive index portion is more than 1.7, the compatibility between the material substances in the composition for a light diffusion film may be excessively lowered.

Therefore, it is preferable that the refractive index of the high refractive index portion in the first structural region is in the range of 1.52 to 1.65, and more preferably in the range of 1.55 to 1.6.

Incidentally, the refractive index of the high refractive index portion can be measured in accordance with JIS K0062.

Further, in the first structural region, it is preferable that the refractive index of the plate-like region (low refractive index portion) having a relatively low refractive index is in the range of 1.4 to 1.5.

The reason is that if the refractive index of the low refractive index portion is less than 1.4, the rigidity of the obtained light diffusion film may be lowered.

On the other hand, when the refractive index of the low refractive index portion exceeds 1.5, the difference in refractive index from the high refractive index portion becomes too small, and it may be difficult to obtain a desired louver structure region.

Therefore, it is preferable that the refractive index of the low refractive index portion in the first structural region is in the range of 1.42 to 1.48, and more preferably in the range of 1.44 to 1.46.

Incidentally, the refractive index in the low refractive index portion can be measured, for example, in accordance with JIS K0062.

(1)-2 width

Further, as shown in Figs. 13a to 13b, in the first structural region, the widths (Sa, Sb) of the high refractive index portion 12 and the low refractive index portion 14 having different refractive indices are preferably 0.1 to 15 μm . The value in the range.

The reason for this is that the width of the plate-like regions is set to a value in the range of 0.1 to 15 μm , whereby the incident light can be more stably reflected in the louver structure region as the first structural region, thereby further improving The angle of incidence dependence from the first structural region and the opening angle of the diffused light.

In other words, when the width of the plate-like region is less than 0.1 μm , it is difficult to display the light diffusibility regardless of the incident angle of the incident light. On the other hand, when the width is a value exceeding 15 μm , the straight light in the louver structure region increases, and the uniformity of light diffusion may be deteriorated.

Therefore, in the first structural region, it is preferable that the width of the plate-like region having a different refractive index is in the range of 0.5 to 10 μm , and more preferably in the range of 1 to 5 μm .

Incidentally, the width, length, and the like of the plate-like region constituting the louver structure region can be calculated by observation with an optical digital microscope.

(1)-3 thickness

Further, as shown in Figs. 13a to 13b, in the first structural region, the thickness (length) La of the high refractive index portion 12 and the low refractive index portion 14 having different refractive indices is preferably 5 to 495 μm . The value in the range.

The reason is that if the thickness is less than 5 μm , the thickness of the louver structure region is insufficient, and incident light that flows straight in the louver structure region increases, and it may be difficult to obtain sufficient incident angle dependency and diffused light. The opening angle.

On the other hand, when the thickness is more than 495 μm , when the composition for a light-diffusion film is irradiated with an active energy ray to form a louver structure region, the traveling direction of photopolymerization is diffused due to the louver structure region formed at an initial stage. It is sometimes difficult to form a desired louver structure area.

Therefore, in the first structural region, it is preferable that the thickness of the plate-like region having the different refractive indices is in the range of 40 to 310 μm , and more preferably in the range of 95 to 255 μm .

It should be noted that, as shown in FIG. 13b, the louver structure region may also be in the first structure region. The upper and lower end portions in the film thickness direction are not formed.

That is, although the width Lb of the lower end portion of the louver structure region is not determined depending on the thickness of the first structure region, it is usually preferably in the range of 0 to 100 μm , preferably in the range of 0 to 50 μm . The value inside is more preferably in the range of 0 to 5 μm .

(1)-4 tilt angle

Further, as shown in FIGS. 13a to 13b, in the first structural region, it is preferable that the high refractive index portion 12 and the low refractive index portion 14 having different refractive indices extend at a constant inclination angle θ a with respect to the film thickness direction.

The reason is that, by making the inclination angle of the plate-like region constant, the incident light can be more stably reflected in the louver structure region as the first structural region, and the incident angle dependency and the diffused light from the first structural region can be further improved. The opening angle.

In addition, as shown in Fig. 13c, it is also preferable to bend the louver structure region.

The reason for this is that by bending the louver structure region, incident light traveling straight in the louver structure region can be reduced, and uniformity of light diffusion can be improved.

In addition, the curved louver structure region can be obtained by irradiating light while changing the irradiation angle of the irradiation light when the first active energy ray line described in the second embodiment is irradiated, but it is also largely Depending on the type of material material that forms the area of the louver structure.

Further, θ a refers to a cross section when the film is cut along a plane perpendicular to the louver structure region extending in either direction along the film surface, and the measured angle with respect to the normal to the film surface is set to The inclination angle (°) of the plate-like area at 0°.

More specifically, as shown in FIG. 13, it means the angle of the narrow side in the angle formed by the normal line of the film surface on the side where the incident light is irradiated and the plate-like area. Incidentally, as shown in FIG. 13a, the inclination angle when the louver is inclined to the left side is marked with the inclination angle when the louver is inclined to the right side as a reference. negative.

(2) The second structural area

The light-diffusing film of the present invention is characterized in that, as a second structure region for isotropically diffusing incident light, a plurality of pillars having a relatively high refractive index are formed in a region having a relatively low refractive index. The column structure area.

Hereinafter, the second structural region will be specifically described.

(2)-1 refractive index

In the second structural region, the difference between the refractive index of the columnar refractive index and the refractive index of the region having a low refractive index is preferably 0.01 or more.

The reason is that, by setting the difference in refractive index to a value of 0.01 or more, incident light can be stably reflected in the column structure region as the second structural region, and the incident angle dependency from the second structural region can be further improved. Sexual and diffuse light opening angles.

In other words, when the difference in refractive index is less than 0.01, the angular range of total reflection of incident light in the column structure region is narrow, and the incident angle dependency is excessively lowered, or the opening angle of the diffused light is excessively changed. narrow.

Therefore, it is preferable that the difference between the refractive index of the pillar in the second structural region and the refractive index of the medium is 0.05 or more, and more preferably 0.1 or more.

Incidentally, the larger the difference in refractive index is, the more preferable. However, from the viewpoint of selecting a material capable of forming a columnar structure region, it is considered that the upper limit is about 0.3.

(2)-2 maximum diameter

Further, as shown in Fig. 14a, in the second structural region, it is preferable that the maximum diameter Sc of the cross section of the pillar is in the range of 0.1 to 15 μm .

The reason for this is that by setting the maximum diameter to a value in the range of 0.1 to 15 μm , the incident light can be more stably reflected in the column structure region as the second structural region, and the second structure can be further improved. The angle of incidence of the region and the angle of opening of the diffused light.

That is, when the maximum diameter is less than 0.1 μm , the light diffusibility is sometimes difficult to display regardless of the incident angle of the incident light. On the other hand, when the maximum diameter is a value exceeding 15 μm , the straight light in the column structure region increases, and the uniformity of light diffusion may be deteriorated.

Therefore, in the second structural region, it is preferable that the maximum diameter of the cross section of the column is in the range of 0.5 to 10 μm , and more preferably in the range of 1 to 5 μm .

In addition, the cross-sectional shape of the columnar is not particularly limited, but is preferably, for example, a circle, an ellipse, a polygon, a profile, or the like.

Further, the cross section of the pillar refers to a section cut along a plane parallel to the surface of the membrane.

Incidentally, the maximum diameter, length, and the like of the column can be calculated by observation with an optical digital microscope.

(2)-3 thickness

Further, in the second structural region, it is preferable that the thickness (length) Lc of the pillar is in a range of 5 to 495 μm .

The reason is that when the thickness is less than 5 μm , the thickness of the pillar is insufficient, and incident light that flows straight in the column structure region increases, and it may be difficult to obtain sufficient incident angle dependency and diffused light. The opening angle.

On the other hand, when the thickness is more than 495 μm , when the composition for a light-diffusion film is irradiated with an active energy ray to form a columnar structure region, the traveling direction of photopolymerization is diffused due to the pillar structure region formed at an initial stage. It is sometimes difficult to form a desired column structure region.

Therefore, in the second structural region, it is preferable that the thickness of the pillar is in the range of 40 to 310 μm , and more preferably in the range of 95 to 255 μm .

Incidentally, as shown in Fig. 14c, the column structure region may not be formed to the upper and lower end portions in the film thickness direction in the second structure region.

That is, although the width Ld of the lower end portion of the column structure region is not formed depending on the thickness of the second structure region, it is usually preferably in the range of 0 to 50 μm , preferably in the range of 0 to 5 μm . The value inside.

(2)-4 distance between pillars

Further, as shown in Fig. 14a, in the second structural region, it is preferable that the distance between the pillars, that is, the space P between the adjacent pillars is a value in the range of 0.1 to 15 μm .

The reason for this is that by setting the distance to a value in the range of 0.1 to 15 μm , the incident light can be more stably reflected in the column structure region as the second structural region, and the second structural region can be further improved. The angle of incidence dependence and the angle of opening of the diffused light.

In other words, when the distance is less than 0.1 μm , it is difficult to display the light diffusibility regardless of the incident angle of the incident light. On the other hand, when the distance is a value exceeding 15 μm , the light traveling straight in the column structure increases, and the uniformity of light diffusion may be deteriorated.

Therefore, in the second structural region, it is preferable that the distance between the pillars is in the range of 0.5 to 10 μm , and more preferably in the range of 1 to 5 μm .

(2)-5 tilt angle

Further, as shown in Figs. 14b to 14c, in the second structural region, the pillars 22 are preferably slanted at a constant inclination angle θ b with respect to the film thickness direction.

The reason for this is that, by making the inclination angle of the pillars constant, it is possible to reflect the incident light more stably in the column structure region as the second structural region, thereby further improving the 2 The angle of incidence of the structural region and the opening angle of the diffused light.

Further, as shown in Fig. 14d, it is also preferable that the pillars are curved.

The reason for this is that by bending the pillars, incident light traveling straight in the column structure region can be reduced, and the uniformity of light diffusion can be further improved.

In addition, when the second active energy ray described in the second embodiment is irradiated, the curved light can be obtained by irradiating light while changing the irradiation angle of the irradiation light, but it is also largely Depending on the type of material material forming the column structure region.

In addition, θ b is a cross section when the film is cut perpendicular to the film surface and the entire column is cut along the axis line, and the measured angle is set with respect to the normal line of the film surface. The inclination angle (°) of the column at 0° (the angle between the normal and the narrow side of the angle formed by the column). Incidentally, the inclination angle when the column is inclined to the left side is marked as negative with respect to the inclination angle when the column is inclined to the right side as shown in Fig. 14b.

(3) Total film thickness

Further, it is preferable that the total film thickness of the light-diffusing film of the present invention is in the range of 50 to 500 μm .

The reason for this is that if the total film thickness of the light-diffusing film is less than 50 μm , the light traveling straight in the column structure region and the louver structure region increases, and it may be difficult to display light diffusibility. On the other hand, when the total film thickness of the light-diffusing film is more than 500 μm , when the composition for the light-diffusing film is irradiated with the active energy ray to form the column structure region and the louver structure region, the column structure formed at the initial stage The region and the louver structure region are diffused in the traveling direction of photopolymerization, and it may be difficult to form a desired column structure region and louver structure region.

Therefore, it is preferable that the total film thickness of the light-diffusing film is in the range of 80 to 350 μm , and more preferably in the range of 100 to 260 μm .

The first structural region and the second structural region are along the film thickness direction of the light diffusion film. It is only necessary to set it in the up and down direction in turn, and there is no particular limitation on the order and number thereof.

(4) Combination of tilt angles

Further, in the case of the light-diffusing film of the present invention, the inclination angle θ a of the plate-like region in the film thickness direction in the first structural region and the film thickness direction in the second structural region are respectively adjusted. The column is inclined at an angle θ b so that its light diffusion characteristics can be changed.

For example, by repeating the incident angle dependency of each structural region, it is possible to suppress not only the fluctuation of the light diffusion characteristics, but also to obtain a good incident angle dependency, and it is also possible to effectively increase the opening angle of the diffused light.

In this case, in the first structural region, it is preferable that the inclination angle θ a with respect to the plate-like region in the film thickness direction is a value within a range of -80 to 80°, and in the second structural region, it is preferable to make The inclination angle θ b of the pillar with respect to the film thickness direction is a value in the range of -80 to 80°, and is preferably such that the absolute value of θ a - θ b is in the range of 0 to 80°. Preferably, the absolute value of θ a - θ b is in the range of 5 to 20 °.

Incidentally, the contents of θ a and θ b herein are as described above.

Further, by shifting the incident angle dependency of each structural region, the light diffusion incident angle region can be effectively and easily expanded.

In this case, in the first structural region, it is preferable that the inclination angle θ a with respect to the plate-like region in the film thickness direction is a value within a range of -80 to 80°, and in the second structural region, it is preferable to make The inclination angle θ b of the pillar with respect to the film thickness direction is a value in the range of -80 to 80°, and is preferably such that the absolute value of θ a - θ b is in the range of 5 to 60°. It is preferable to make the absolute value of θ a - θ b in the range of 20 to 45°.

(5) Use

Moreover, as shown in FIG. 15, it is preferable to use the light-diffusion film obtained by the manufacturing method of this invention for the reflective liquid crystal display device 100.

The reason for this is that the light diffusion film obtained by the production method of the present invention can condense external light and efficiently transmit it to the inside of the liquid crystal display device, and the light can be emitted. As a light source, it is possible to efficiently diffuse.

Therefore, the light-diffusing film of the present invention is preferably disposed on the upper surface or the lower surface of the liquid crystal cell 110 composed of the glass plate (104, 108), the liquid crystal 106, the specular reflection plate 107, and the like, and is used as the reflective liquid crystal display device 100. The light diffusing plate 103 is used.

In the light-diffusing film of the present invention, the polarizing plate 101 and the retardation film 102 are provided, whereby a wide viewing angle polarizing plate and a wide viewing-field retardation plate can be obtained.

Example

Hereinafter, a method of producing a light-diffusing film of the present invention will be described in further detail with reference to examples.

[Example 1]

1. Synthesis of (B) components

In the container, polypropylene glycol (PPG) 1 mol having a weight average molecular weight of 9,200 as a component (B2) is contained, and in contrast, isophorone diisocyanate (IPDI) 2 mol as a component (B1) is contained and After the (B3) component of 2-hydroxyethyl methacrylate (HEMA) 2 moles, polymerization was carried out according to a conventional method to obtain a polyether urethane methacrylate having a weight average molecular weight of 9,900.

The weight average molecular weight of the polypropylene glycol and the polyether urethane methacrylate is a polystyrene equivalent value measured by gel permeation chromatography (GPC) under the following conditions.

. GPC measuring device: manufactured by TOSOH Co., Ltd., HLC-8020

. GPC column: manufactured by TOSOH Co., Ltd. (hereinafter, it is described in order of passage)

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

. Determination of solvent: tetrahydrofuran

. Measuring temperature: 40 ° C

2. Preparation of composition for light diffusion film

Then, the weight average molecular weight 268 represented by the following formula (3) as the component (A) is added to 100 parts by weight of the polyether urethane methacrylate having a weight average molecular weight of 9900 as the component (B). 100 parts by weight of o-phenylphenoxyethoxyethyl acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ESTER A-LEN-10) and 10 parts by weight of 2-hydroxy-2-methylpropiophenone as component (C) After the mixture, the mixture was heated and mixed at 80 ° C to obtain a composition for a light-diffusing film. The refractive index of the component (A) and the component (B) is measured by an Abbe refractometer (product name "Abe refractometer DR-M2", Na light source, wavelength 589 nm) according to JIS K0062. The results were 1.58 and 1.46, respectively.

3. Coating of composition for light diffusion film

Next, the sheet-like transparent polyethylene terephthalate film (hereinafter referred to as PET) as a process sheet is coated with the composition for anisotropic light-diffusing film to form a film thickness of 200 μm . Coating layer.

4. Light curing of the coating layer

(1) The first ultraviolet irradiation

Next, an ultraviolet irradiation apparatus (ECS-4011GX, manufactured by EYE GRAPHICS Co., Ltd.) obtained by attaching a cold lens for collecting light to a linear high-pressure mercury lamp (diameter: 25 mm) as shown in Fig. 9a was prepared.

Next, a light shielding plate is provided on the heat radiation cut filter frame, and the ultraviolet light irradiated on the surface of the coating layer is set to be composed of a coating layer and PET when viewed from the longitudinal direction of the linear ultraviolet lamp. When the normal direction of the laminate is set to 0°, the irradiation angle of ultraviolet rays directly emitted from the lamp ( θ 3 in Fig. 9b) is -35°.

At this time, the height of the lamp from the coating layer was set to 500 mm, and the peak illuminance was 1.7 mW/cm ² .

In addition, in order to prevent the reflected light of the light shielding plate or the like from becoming stray light inside the irradiation device, it affects the photocuring of the coating layer, and a light shielding plate is also provided in the vicinity of the conveyor to irradiate only the ultraviolet rays directly emitted from the lamp to the coating layer. The way to set.

Next, the coating layer was irradiated with ultraviolet rays by moving the coating layer to the right side in Fig. 9a at a speed of 0.2 m/min.

(2) Second ultraviolet irradiation

Then, after the first ultraviolet irradiation step, the exposed surface side of the coating layer was laminated with a release film having a thickness of 38 μm (SP-PET382050, manufactured by Lintec Co., Ltd.).

Next, an ultraviolet irradiation apparatus (EYE GRAPHICS Co., Ltd., manufactured by EYE GRAPHICS Co., Ltd.), which is equipped with a cold-light mirror for collecting light in a high-pressure mercury lamp (25 mm in diameter) as shown in Fig. 9a, is prepared. ECS-4011GX).

Next, between the linear ultraviolet lamp and the coating layer, an irradiation light parallelizing unit in which a plurality of plate-like members as shown in FIG. 10a are arranged in parallel is disposed.

At this time, when viewed from above the film, the irradiation light parallelizing unit is disposed in a direction orthogonal to the axial direction of the linear ultraviolet lamp, that is, θ 4 = 90° in Fig. 11a.

Then, the ultraviolet light is irradiated from the linear ultraviolet lamp by the irradiation light parallelizing means, so that the parallel light having a parallelism of 2 or less is separated by the peeling film so that the irradiation angle ( θ 3 in FIG. 9b) is almost 0°. The coating layer was irradiated, and as a result, a light diffusion film having a total film thickness of 195 μm was obtained.

The peak illuminance at this time was set to 1.84 mW/cm ² , the lamp height was set to 500 mm, and the moving speed of the coating layer was set to 1 m/min.

In addition, the film thickness of the light-diffusion film can be measured using a constant-pressure thickness measuring device (TECLOCK PG-02J, manufactured by Takara Seisakusho Co., Ltd.).

Further, the interval (L1 in Fig. 11a) of the plurality of plate-like members in the illumination light parallelizing unit is 20 mm, the width of the plate-like member (L2 in Fig. 11a) is 300 mm, and the thickness of the plate-like member is 1 mm, material It is an aluminized steel that has been subjected to heat-resistant black coating.

Further, the length from the upper end to the lower end of the illumination light parallelizing unit (L5 in FIG. 11b) is 200 mm, and the distance between the upper end of the illumination light parallelizing unit and the lower end of the linear ultraviolet lamp (L6 in FIG. 11b) is 200 mm, the distance between the lower end of the illumination light parallelizing unit and the surface of the coating layer (L7 in Fig. 11b) was 100 mm.

Further, it was confirmed that the obtained light-diffusing film was a light-diffusing film having a louver structure having an inclination angle of -23° and a columnar inclination angle of -10°.

Incidentally, Fig. 16 is a schematic view showing a cross section of the film when cut along a plane perpendicular to the plate-like region in the louver structure.

Further, the film thickness of the first structural region was 120 μm , and the film thickness of the second structural region was 75 μm .

Further, a cross-sectional photograph of the obtained light-diffusing film is shown in Figs. 17a to 17b. Fig. 17a is a photograph of a cross section when the film is cut along a plane perpendicular to the plate-like region in the louver structure, and Fig. 17b is a photograph of a cross section when the film is cut along a plane perpendicular to the cut surface in Fig. 17a.

Moreover, as can be seen from FIGS. 17a to 17b, an irradiation light parallelizing unit in which linear high-pressure mercury lamps and a plurality of plate-like members are arranged in parallel is used instead of the ultraviolet point light source having high parallelism as shown in the reference example described later. Also in the same manner as the reference example, a laminated structure of the louver structure region and the column structure region can be obtained.

In addition, although the data is not shown, the light diffusing film is also measured in Example 1 using a variable angle colorimeter (Suga Test Instruments Co., Ltd. VC-2) as described later in Reference Example 1. Light diffusion characteristics.

As a result, it has been confirmed that when the incident angle θ 1 of the incident light is about -20°, it is difficult to cause diffusion of light, but when the incident angle θ 1 = -10 to 0°, the directions based on the column structure region are generated. Isotropic light diffusion, when the incident angle θ 1 = -60 ~ -30 °, anisotropic light diffusion based on the louver structure region is generated, and the light diffusion angle dependence on the two structural regions can be shifted Effectively expand the light diffusion incident angle region.

[Example 2]

In Embodiment 2, the irradiation light parallelizing unit is changed to an irradiation light parallelizing unit as an assembly of a plurality of cylindrical members as shown in FIG. 10b, and the moving speed of the coating layer is changed to 0.5 m/min. In the same manner as in the first embodiment, light having a slant angle of -23° and a columnar inclination angle of 3° was obtained in the same manner as in Example 1 except that the peak illuminance of the surface of the coating layer was 1.22 mW/cm ² . Diffusion film.

Incidentally, Fig. 18 is a schematic view showing a cross section of the film when cut along a plane perpendicular to the plate-like region in the louver structure.

Further, the film thickness of the first structural region was 120 μm , and the thickness of the second structural region was 75 μm .

At this time, the planar shape of the opening portion of the cylindrical member in the irradiation light parallelizing unit is hexagonal, and the maximum diameter of the cylindrical member (L3" in FIG. 12b) is 10 mm, and the assembly of the plurality of cylindrical members The width (L4 in Fig. 12a) was 30 nm, and the thickness of the partition wall of the cylindrical portion in the cylindrical assembly was 0.2 mm, and the material was an aluminized steel material to which heat-resistant black coating was applied.

Further, a cross-sectional photograph of the obtained light-diffusing film is shown in Figs. 19a to 19b. Fig. 19a is a photograph of a cross section when the film is cut along a plane perpendicular to the plate-like region in the louver structure, and Fig. 19b is a photograph of a cross section when the film is cut along a plane perpendicular to the cut surface in Fig. 19a.

Further, as is clear from FIGS. 19a to 19b, even in the case of the ultraviolet point light source having a high parallelism as shown in the reference example described later, the irradiation light which is arranged by the linear high-pressure mercury lamp and the plurality of cylindrical members is parallelized. In the case of a so-called pseudo-parallel light source composed of a module, a laminated structure of a louver structure region and a column structure region can be obtained similarly to the reference example.

Incidentally, although the data is not shown, the light diffusion characteristics of the light diffusion film are also measured in the second embodiment using a variable angle colorimeter as described later in Reference Example 1.

As a result, it has been confirmed that when the incident angle θ 1 of the incident light is about -20°, it is difficult to generate light diffusion, but when the incident angle θ 1 = -10 to 0°, each of the column-based structural regions is generated. Isotropic light diffusion, when the incident angle θ 1 = -60 ~ -30 °, anisotropic light diffusion based on the louver structure region is generated, by shifting the angle dependence of light diffusion incidence based on the two structural regions, thereby It is possible to effectively enlarge the light diffusion incident angle region.

[Reference Example 1]

1. Manufacturing of light diffusing film

In Reference Example 1, a light-diffusing film was obtained in the same manner as in Example 1 except that the θ 3 of the first ultraviolet ray irradiation was changed to −40°, and the second ultraviolet ray irradiation was performed as follows.

In other words, a device having a parallelism of 2 or less by a uniform exposure adapter in which an OPTION is mounted in an ultraviolet light source (HYPERCURE 200, manufactured by Yamashita Electric Co., Ltd.) is used as an incident angle of parallel light ( θ 3 in Fig. 9). The film was irradiated through a release film at a temperature of 40° to obtain a light diffusion film having a total film thickness of 195 μm .

The peak illuminance at this time was set to 5 mW/cm ² , the lamp height was set to 800 mm, and the moving speed of the coating layer was set to 0.5 m/min.

Further, it has been confirmed that the obtained light-diffusing film-based louver structure has a light-diffusing film having an inclination angle of -27° and a columnar inclination angle of 27°.

Incidentally, Fig. 20a is a schematic view showing a cross section of the film when cut along a plane perpendicular to the plate-like region in the louver structure.

Further, the film thickness of the first structural region was 120 μm , and the thickness of the second structural region was 75 μm .

Further, a cross-sectional photograph of the obtained light-diffusing film is shown in Figs. 21a to 21b. Fig. 21a is a photograph of a cross section when the film is cut along a plane perpendicular to the plate-like region in the louver structure, and Fig. 21b is a photograph of a cross section when the film is cut along a plane perpendicular to the cut surface in Fig. 21a.

2. Determination

Using a variable angle colorimeter, as shown in Fig. 20a, light was incident on the film at an incident angle θ 1 = 60° from above the obtained light diffusing film (C light source, viewing angle of 2°).

Next, the expansion of the diffused light diffused by the light diffusion film and the luminance (%) distribution thereof were measured. The above measurement results are shown on the horizontal axis of which the value of the vertical axis of the scatter diagram shown in Fig. 20c is 0°.

That is, the value of the horizontal axis represents the range of the angle of enlargement (°) of the diffused light, and the plotted color indicates the brightness (%) of the diffused light diffused to the angle.

Here, in terms of the relationship between the color and brightness (%) of the plot, the closer the color of the plot is to red, the closer the brightness is to 100%, the closer the color of the plot is to green, indicating that the closer the brightness is to 50%, plotting The closer the color is to dark blue, the closer the brightness is to 0%. Should be explained in detail The situation is shown in Figure 20b.

In addition, in order to further measure the spread of the diffused light in the width direction of the incident light and the distribution of the luminance (%), the light diffusing film is placed on the same plane with a predetermined point on the surface of the light diffusing film as a center. The same measurement was carried out while rotating in the range of -80 to 80°.

Incidentally, the angle of the rotation refers to an angle of rotation when the angle of the light diffusion film at the time of the measurement is 0°. For example, the measurement result when the light diffusion film is rotated by 20° is shown on the horizontal axis of which the value of the vertical axis of the scatter diagram shown in Fig. 20c is 20°.

Therefore, for the scattergram shown in Fig. 20c, for example, the region of the diffused light distribution having a luminance of 30% or more is a region surrounded by a broken line in Fig. 20c.

Next, as shown in FIGS. 20d to 20k, the incident angle θ 1 of the light diffusing film is changed to 50°, 40°, 30°, 0°, -30°, -40°, -50°, -60°, respectively. The expansion of the diffused light and the distribution of the luminance (%) thereof were measured in the same manner as in the case of the incident angle θ 1 = 60°.

3. Results

As shown in Figs. 20c to 20k, in the light-diffusing film of Reference Example 1, although the light diffusion is difficult to occur in the range of the incident angle θ 1 = 0° of the incident light, the incident angle θ 1 = 30 In the range of ~60°, isotropic light diffusion based on the column structure region is generated.

Further, when the incident angle θ 1 = -60 to -30 °, anisotropic light diffusion based on the louver structure region occurs.

Therefore, it is understood that the light diffusion incident angle region can be effectively enlarged by shifting the light diffusion incident angle dependency based on the two structural regions.

[Reference Example 2]

In the reference example 2, when the coating layer was cured, the θ 3 of the first ultraviolet irradiation was changed to 40°, and the louver structure was observed to have a tilt angle of 27° in the same manner as in Reference Example 1. A light diffusing film having a tilt angle of 27°.

Incidentally, Fig. 22 is a schematic view showing a cross section of the film when cut along a plane perpendicular to the plate-like region in the louver structure.

In addition, the expansion of the diffused light and the distribution of the luminance (%) thereof were carried out in the same manner as in Reference Example 1 except that the incident angle θ 1 of the light-diffusing film was 25°, 35°, 45°, and 55°, respectively. The measurement was carried out.

As a result, in the light diffusion film of Reference Example 2, the light diffusion incident angle dependence in the louver structure region and the column structure region almost overlaps, and the light diffusion incident angle region is in the range of the incident angle θ 1 = 25 to 55°. A narrower range.

However, it has been confirmed that the light-diffusing film of Reference Example 2 has higher uniformity of diffused light than Comparative Examples 1 and 2 to be described later, and the diffused light in the width direction of the incident light is larger than that of Comparative Examples 3 and 4. .

[Reference Example 3]

In the reference example 3, the louver structure was obtained in the same manner as in the reference example 1 except that the θ 3 of the first ultraviolet ray irradiation was changed to 40° and the incident angle of the parallel light irradiated by the second ultraviolet ray was changed to 0°. A light diffusion film having a tilt angle of 27° and a column angle of inclination of 0°.

Incidentally, Fig. 23a is a schematic view showing a cross section of the film when cut along a plane perpendicular to the plate-like region in the louver structure.

Further, as shown in FIGS. 23b to 23h, the incident angle θ 1 with respect to the light diffusion film is 0°, 10°, 20°, 30°, 40°, 50°, 60°, respectively, and In the same manner as in Reference Example 1, the expansion of the diffused light and the distribution of the luminance (%) thereof were measured.

As a result, as shown in the graphs 23b to 23h, in the light-diffusing film of Reference Example 3, when the incident angle θ 1 of the incident light is about 20°, it is difficult to cause light diffusion, but at the incident angle θ 1 When the range of =0~10°, the isotropic light diffusion based on the column structure region is generated. When the incident angle θ 1=30~60°, the anisotropic light diffusion based on the louver structure region is generated, and the The light diffusion incidence angle dependence of the two structural regions is shifted, so that the light diffusion incident angle region can be effectively enlarged.

[Reference Example 4]

In the reference example 4, the louver structure was obtained in the same manner as in Reference Example 1 except that the θ 3 of the first ultraviolet ray irradiation was changed to 40° and the incident angle of the parallel light of the second ultraviolet ray was changed to 20°. A light diffusing film having a tilt angle of 27° and a column angle of inclination of 14°.

Incidentally, Fig. 24a is a schematic view showing a cross section of the film when cut along a plane perpendicular to the plate-like region in the louver structure.

In addition, as shown in Figs. 24b to 24g, the incident angle θ 1 to the light-diffusing film was 5°, 15°, 25°, 35°, 45°, and 55°, respectively, and the same as in Reference Example 1. The ground is measured for the spread of diffused light and the distribution of its brightness (%).

As a result, as shown in Figs. 24b to 24g, in the light diffusion film of Reference Example 4, when the incident angle θ 1 of the incident light is in the range of 5 to 25°, isotropic light diffusion based on the column structure region occurs. When the incident angle θ 1 is in the range of 25 to 55°, anisotropic light diffusion based on the louver structure region is generated, and although the angle of incidence of the light diffusion based on the two structural regions is shifted, a part is repeated, thereby enabling Effectively expand the light diffusion incident angle region.

[Comparative Example 1]

In Comparative Example 1, the first ultraviolet ray irradiation for forming the louver structure region is not performed, and the incident angle of the parallel light for the second ultraviolet ray irradiation for forming the pillar structure region is changed to 0°, and In the same manner as in Reference Example 1, a light diffusion film having only a columnar structure having an inclination angle of 0° in the entire region corresponding to the first structural region and the second structural region was obtained.

It should be noted that Fig. 25a shows the cutting along the plane perpendicular to the plate-like area in the louver structure. Schematic diagram of the cross section of the film.

In addition, as shown in FIGS. 25b to 25j, the incident angle θ 1 of the light diffusing film is 20°, 15°, 10°, 5°, 0°, -5°, -10°, -15°, respectively. In addition to the above, the expansion of the diffused light and the distribution of the luminance (%) thereof were measured in the same manner as in Reference Example 1.

As a result, as shown in FIGS. 25b to 25j, the light diffusion film of Comparative Example 1 has only a columnar structure, and therefore the light diffusion incident angle region is a relatively narrow range such as a range of θ 1 = -15 to 15°.

Further, it is understood that the center portion of the diffused light is particularly brighter than other portions, and the uniformity of the diffused light is low.

[Comparative Example 2]

In Comparative Example 2, the first ultraviolet ray irradiation for forming the louver structure region was not performed, and the incident angle of the parallel light used for the second ultraviolet ray irradiation for forming the columnar structure region was changed to 40°, and the reference was made to In the same manner as in Example 1, a light diffusion film having a columnar structure having an inclination angle of 27° as a whole in the region corresponding to the first structural region and the second structural region was obtained.

Incidentally, Fig. 26a is a schematic view showing a cross section of the film when cut along a plane perpendicular to the plate-like region in the louver structure.

Further, as shown in FIGS. 26b to 26k, the incident angle θ 1 of the light diffusing film is 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60, respectively. In the same manner as in Reference Example 1, the expansion of the diffused light and the distribution of the luminance (%) thereof were measured.

As a result, as shown in FIGS. 26b to 26k, the light diffusion film of Comparative Example 2 has only a columnar structure, and therefore the light diffusion incident angle region is a relatively narrow range like θ 1 = 25 to 60°.

Further, it is understood that the center portion of the diffused light is particularly brighter than other portions, and the uniformity of the diffused light is low.

[Comparative Example 3]

In Comparative Example 3, θ 3 of the first ultraviolet ray irradiation was changed to 0°, and as the second ultraviolet ray irradiation, scattered light having a peak illuminance of 13.7 mW/cm ² and an integrated light amount of 213.6 mJ/cm ² was irradiated. In the same manner as in Reference Example 1, a light-diffusing film having a louver structure region in which the inclination angle of the first structural region was 0° and a region in which the louver structure was not formed was obtained.

Incidentally, Fig. 27a is a schematic view showing a cross section of the film when cut along a plane perpendicular to the plate-like region in the louver structure.

Further, as shown in FIGS. 27b to 27h, the incident angle θ 1 of the light diffusing film is 20°, 15°, 10°, 5°, 0°, -5°, and -10°, respectively. In the same manner as in Reference Example 1, the expansion of the diffused light and the distribution of the luminance (%) thereof were measured.

As a result, as shown in FIGS. 27b to 27h, since the light diffusion film of Comparative Example 3 has only the louver structure, the light diffusion angle region is a relatively narrow range like θ 1 = -5 to 15.

Further, it is understood that the anisotropy of the diffused light is large, and the expansion of the diffused light in the width direction of the incident light is small.

[Comparative Example 4]

In Comparative Example 4, θ 3 of the first ultraviolet ray irradiation was changed to 40°, and as the second ultraviolet ray irradiation, scattered light having a peak illuminance of 13.7 mW/cm ² and an integrated light amount of 213.6 mJ/cm ² was irradiated. In the same manner as in Reference Example 1, a light-diffusing film having a louver structure region having a tilt angle of 27° as the first structure region and a region where the louver structure was not formed was obtained.

Incidentally, Fig. 28a is a schematic view showing a cross section of the film when cut along a plane perpendicular to the plate-like region in the louver structure.

Further, as shown in FIGS. 28b to 28i, the incident angle θ 1 of the light diffusing film is 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, respectively. A light diffusion film was produced in the same manner as in Reference Example 1.

Further, as shown in FIGS. 28b to 28i, the light diffusion film of Comparative Example 4 has only a louver structure, and therefore the light diffusion angle region is a relatively narrow range such as θ 1 = 30 to 60°.

Further, it is understood that the anisotropy of the diffused light is large, and the expansion of the diffused light in the width direction of the incident light is small.

Industrial availability

As described in detail above, according to the present invention, by providing a louver structure region for diffusing anisotropic light into incident light in a film, and a column structure region for diffusing incident light to isotropic light, it is possible to obtain A light diffusing film having a good incident angle dependency and a wide range of light diffusion incident angles.

Further, by sequentially performing the first active energy ray irradiation for forming the louver structure region and the second active energy ray irradiation by the irradiation light parallelizing unit for forming the pillar structure region, the linear light source can be easily used. A light diffusion film having the above characteristics was obtained.

Therefore, the light diffusion film obtained by the manufacturing method of the present invention can be provided to the viewing angle control film, the viewing angle expansion film, and the projection screen in addition to the light control film in the reflective liquid crystal device. It is expected to contribute significantly to the improvement of such quality and manufacturing efficiency.

10‧‧‧A louver structure area (first structural area) in which incident light is diffused by anisotropic light

20‧‧‧Column structure area (second structure area) in which incident light is isotropically diffused

30‧‧‧Light diffusing film

Claims (10)

A method for producing a light-diffusing film, comprising: a first structure region for diffusing incident light by anisotropic light; and a light diffusion film for a second structure region for diffusing incident light into isotropic light The manufacturing method includes the following steps (a) to (d): (a) a step of preparing a composition for a light-diffusing film, and (b) applying the composition for a light-diffusing film to a process sheet to form a coating layer. Step (c) directly exposing the exposed surface of the coating layer to the first active energy ray, and forming a plurality of plate-like regions having different refractive indices as the first structural region under the coating layer a louver structure region in which any one of the film faces is alternately arranged, and a portion in which a region of the louver structure is not formed is left over the coating layer, and (d) a release film layer having ultraviolet ray permeability After the exposed surface of the coating layer is formed, the coating layer is further irradiated with the second active energy ray through the release film, and the refractive index is relatively high as the second structural region in the region where the louver structure is not formed. Multiple pillars with relatively low refractive index A column structure region formed in the region, wherein the coating layer is irradiated with the irradiation light from the linear light source by the irradiation light parallelizing unit as the second active energy ray. The method of manufacturing a light diffusing film according to claim 1, wherein the illuminating light parallelizing unit is composed of a plurality of plate-like members, and the plurality of plate-like members are respectively arranged in parallel when viewed from above the film. Made of. The method for producing a light-diffusing film according to claim 2, wherein an interval between adjacent ones of the plurality of plate-like members is a value in a range of from 1 to 100 mm. The method for producing a light-diffusing film according to claim 2, wherein the irradiation light parallelizing unit is disposed in a direction in which the plate-like member intersects the axial direction of the linear light source when viewed from above the film. The method for producing a light-diffusing film according to claim 1, wherein the irradiation light parallelizing unit is an assembly of a plurality of cylindrical members. The method for producing a light-diffusing film according to claim 5, wherein the cylindrical member has a maximum diameter in a range of from 1 to 100 mm. The method for producing a light-diffusing film according to claim 1, wherein the length of the irradiation light parallelizing unit from the upper end to the lower end is a value in the range of 10 to 1000 mm. The method for producing a light-diffusing film according to claim 1, wherein a distance between an upper end of the irradiation light parallelizing unit and a lower end of the linear light source is a value in a range of 0 to 1000 mm. The method for producing a light-diffusing film according to claim 1, wherein a distance between a lower end of the irradiation light parallelizing unit and a surface of the coating layer is a value in a range of 0 to 1000 mm. The method for producing a light-diffusing film according to claim 1, wherein in the second active energy ray irradiation, the parallelism of the illuminating light parallelized by the illuminating light parallelizing unit is 10°. The following values.